Espruino WiFi Software Reference

This is a software reference containing only the functionality available in Espruino WiFi. For a reference showing all available functionality, click here.

Version 2v24

Globals

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Methods and Fields

variable __FILE__

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Call type:

variable __FILE__

Returns

The filename of the JavaScript that is currently executing

Description

The filename of the JavaScript that is currently executing.

If load has been called with a filename (eg load("myfile.js")) then __FILE__ is set to that filename. Otherwise (eg load()) or immediately after booting, __FILE__ is not set.

function analogRead

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Call type:

function analogRead(pin)

Parameters

pin - The pin to use
You can find out which pins to use by looking at your board's reference page and searching for pins with the ADC markers.

Returns

The Analog Value of the Pin between 0(GND) and 1(VCC). See below.

Description

Get the analogue value of the given pin.

This is different to Arduino which only returns an integer between 0 and 1023

However only pins connected to an ADC will work (see the datasheet)

Note: if you didn't call pinMode beforehand then this function will also reset pin's state to "analog"

Note: Jolt.js motor driver pins with analog inputs are scaled with a potential divider, and so those pins return a number which is the actual voltage.

function analogWrite

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Call type:

function analogWrite(pin, value, options)

Parameters

pin - The pin to use
You can find out which pins to use by looking at your board's reference page and searching for pins with the PWM or DAC markers.

value - A value between 0 and 1

options - An object containing options for analog output - see below

Description

Set the analog Value of a pin. It will be output using PWM.

Objects can contain:

  • freq - pulse frequency in Hz, e.g. analogWrite(A0,0.5,{ freq : 10 }); - specifying a frequency will force PWM output, even if the pin has a DAC
  • soft - boolean, If true software PWM is used if hardware is not available.
  • forceSoft - boolean, If true software PWM is used even if hardware PWM or a DAC is available

On nRF52-based devices (Puck.js, Pixl.js, MDBT42Q, etc) hardware PWM runs at 16MHz, with a maximum output frequency of 4MHz (but with only 2 bit (0..3) accuracy). At 1Mhz, you have 4 bits (0..15), 1kHz = 14 bits and so on.

Note: if you didn't call pinMode beforehand then this function will also reset pin's state to "output"

variable arguments

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Call type:

variable arguments

Returns

An array containing all the arguments given to the function

Description

A variable containing the arguments given to the function:


function hello() {
  console.log(arguments.length, JSON.stringify(arguments));
}
hello()        // 0 []
hello("Test")  // 1 ["Test"]
hello(1,2,3)   // 3 [1,2,3]

Note: Due to the way Espruino works this is doesn't behave exactly the same as in normal JavaScript. The length of the arguments array will never be less than the number of arguments specified in the function declaration: (function(a){ return arguments.length; })() == 1. Normal JavaScript interpreters would return 0 in the above case.

function atob

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Call type:

function atob(base64Data)

Parameters

base64Data - A string of base64 data to decode

Returns

A string containing the decoded data

Description

Decode the supplied base64 string into a normal string

Note: This is not available in devices with low flash memory

variable BTN

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Call type:

variable BTN

Returns

Button 1

variable BTN1

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Call type:

variable BTN1

Returns

BTN1

function btoa

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Call type:

function btoa(binaryData)

Parameters

binaryData - A string of data to encode

Returns

A base64 encoded string

Description

Encode the supplied string (or array) into a base64 string

Note: This is not available in devices with low flash memory

function changeInterval

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Call type:

function changeInterval(id, time)

Parameters

id - The id returned by a previous call to setInterval

time - The new time period in ms

Description

Change the Interval on a callback created with setInterval, for example:

var id = setInterval(function () { print('foo'); }, 1000); // every second

changeInterval(id, 1500); // now runs every 1.5 seconds

This takes effect immediately and resets the timeout, so in the example above, regardless of when you call changeInterval, the next interval will occur 1500ms after it.

function clearInterval

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Call type:

function clearInterval(id, ...)

Parameters

id, ... - The id returned by a previous call to setInterval. Only one argument is allowed.

Description

Clear the Interval that was created with setInterval, for example:

var id = setInterval(function () { print('foo'); }, 1000);

clearInterval(id);

If no argument is supplied, all timeouts and intervals are stopped.

To avoid accidentally deleting all Intervals, if a parameter is supplied but is undefined then an Exception will be thrown.

function clearTimeout

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Call type:

function clearTimeout(id, ...)

Parameters

id, ... - The id returned by a previous call to setTimeout. Only one argument is allowed.

Description

Clear the Timeout that was created with setTimeout, for example:

var id = setTimeout(function () { print('foo'); }, 1000);

clearTimeout(id);

If no argument is supplied, all timeouts and intervals are stopped.

To avoid accidentally deleting all Timeouts, if a parameter is supplied but is undefined then an Exception will be thrown.

function clearWatch

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Call type:

function clearWatch(id, ...)

Parameters

id, ... - The id returned by a previous call to setWatch. Only one argument is allowed. (or pass nothing to clear all watches)

Description

Clear the Watch that was created with setWatch. If no parameter is supplied, all watches will be removed.

To avoid accidentally deleting all Watches, if a parameter is supplied but is undefined then an Exception will be thrown.

function decodeURIComponent

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Call type:

function decodeURIComponent(str)

Parameters

str - A string to decode from a URI

Returns

A string containing the decoded data

Description

Convert any groups of characters of the form '%ZZ', into characters with hex code '0xZZ'

Note: This is not available in devices with low flash memory

function digitalPulse

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Call type:

function digitalPulse(pin, value, time)

Parameters

pin - The pin to use

value - Whether to pulse high (true) or low (false)

time - A time in milliseconds, or an array of times (in which case a square wave will be output starting with a pulse of 'value')

Description

Pulse the pin with the value for the given time in milliseconds. It uses a hardware timer to produce accurate pulses, and returns immediately (before the pulse has finished). Use digitalPulse(A0,1,0) to wait until a previous pulse has finished.

e.g. digitalPulse(A0,1,5); pulses A0 high for 5ms. digitalPulse(A0,1,[5,2,4]); pulses A0 high for 5ms, low for 2ms, and high for 4ms

Note: if you didn't call pinMode beforehand then this function will also reset pin's state to "output"

digitalPulse is for SHORT pulses that need to be very accurate. If you're doing anything over a few milliseconds, use setTimeout instead.

function digitalRead

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Call type:

function digitalRead(pin)

Parameters

pin - The pin to use

Returns

The digital Value of the Pin

Description

Get the digital value of the given pin.

Note: if you didn't call pinMode beforehand then this function will also reset pin's state to "input"

If the pin argument is an array of pins (e.g. [A2,A1,A0]) the value returned will be an number where the last array element is the least significant bit, for example if A0=A1=1 and A2=0, digitalRead([A2,A1,A0]) == 0b011

If the pin argument is an object with a read method, the read method will be called and the integer value it returns passed back.

function digitalWrite

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Call type:

function digitalWrite(pin, value)

Parameters

pin - The pin to use

value - Whether to write a high (true) or low (false) value

Description

Set the digital value of the given pin.


digitalWrite(LED1, 1); // light LED1
digitalWrite([LED1,LED2,LED3], 0b101); // lights LED1 and LED3

Note: if you didn't call pinMode(pin, ...) or Pin.mode(...) beforehand then this function will also reset pin's state to "output"

If pin argument is an array of pins (e.g. [A2,A1,A0]) the value argument will be treated as an array of bits where the last array element is the least significant bit.

In this case, pin values are set least significant bit first (from the right-hand side of the array of pins). This means you can use the same pin multiple times, for example digitalWrite([A1,A1,A0,A0],0b0101) would pulse A0 followed by A1.

In 2v22 and later firmwares, using a boolean for the value will set all pins in the array to the same value, eg digitalWrite(pins, value?0xFFFFFFFF:0). Previously digitalWrite with a boolean behaved like digitalWrite(pins, value?1:0) and would only set the first pin.

If the pin argument is an object with a write method, the write method will be called with the value passed through.

function dump

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Call type:

function dump()

Description

Output current interpreter state in a text form such that it can be copied to a new device

Espruino keeps its current state in RAM (even if the function code is stored in Flash). When you type dump() it dumps the current state of code in RAM plus the hardware state, then if there's code saved in flash it writes "// Code saved with E.setBootCode" and dumps that too.

Note: 'Internal' functions are currently not handled correctly. You will need to recreate these in the onInit function.

Note: This is not available in devices with low flash memory

function echo

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Call type:

function echo(echoOn)

Parameters

echoOn -

Description

Should Espruino echo what you type back to you? true = yes (Default), false = no. When echo is off, the result of executing a command is not returned. Instead, you must use 'print' to send output.

function edit

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Call type:

function edit(funcName)

Parameters

funcName - The name of the function to edit (either a string or just the unquoted name)

Description

Fill the console with the contents of the given function, so you can edit it.

NOTE: This is a convenience function - it will not edit 'inner functions'. For that, you must edit the 'outer function' and re-execute it.

Note: This is not available in devices with low flash memory

function encodeURIComponent

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Call type:

function encodeURIComponent(str)

Parameters

str - A string to encode as a URI

Returns

A string containing the encoded data

Description

Convert a string with any character not alphanumeric or - _ . ! ~ * ' ( ) converted to the form %XY where XY is its hexadecimal representation

Note: This is not available in devices with low flash memory

function eval

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Call type:

function eval(code)

Parameters

code -

Returns

The result of evaluating the string

Description

Evaluate a string containing JavaScript code

function getPinMode

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Call type:

function getPinMode(pin)

Parameters

pin - The pin to check

Returns

The pin mode, as a string

Description

Return the current mode of the given pin. See pinMode for more information on returned values.

Note: This is not available in devices with low flash memory

function getSerial

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Call type:

function getSerial()

Returns

The board's serial number

Description

Get the serial number of this board

function getTime

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Call type:

function getTime()

Returns

See description above

Description

Return the current system time in Seconds (as a floating point number)

variable global

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Call type:

variable global

Returns

The global scope

Description

A reference to the global scope, where everything is defined.

global is used in Node.js. Consider using the identical globalThis as it was introduced in the ECMAScript spec.

variable globalThis

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Call type:

variable globalThis

Returns

The global scope

Description

A reference to the global scope, where everything is defined.

This is identical to global but was introduced in the ECMAScript spec.

variable HIGH

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Call type:

variable HIGH

Returns

Logic 1 for Arduino compatibility - this is the same as just typing 1

I2C1

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Instance of I2C

Description

The first I2C port

Note: This is only available in devices with more than 1 ESPR_I2C peripherals

I2C2

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Instance of I2C

Description

The second I2C port

Note: This is only available in devices with more than 2 ESPR_I2C peripherals

I2C3

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Instance of I2C

Description

The third I2C port

Note: This is only available in devices with more than 3 ESPR_I2C peripherals

variable Infinity

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Call type:

variable Infinity

Returns

Positive Infinity (1/0)

function isFinite

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Call type:

function isFinite(x)

Parameters

x -

Returns

True is the value is a Finite number, false if not.

Description

Is the parameter a finite number or not? If needed, the parameter is first converted to a number.

function isNaN

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Call type:

function isNaN(x)

Parameters

x -

Returns

True is the value is NaN, false if not.

Description

Whether the x is NaN (Not a Number) or not

variable LED

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Call type:

variable LED

Returns

LED1

variable LED1

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Call type:

variable LED1

Returns

LED1

variable LED2

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Call type:

variable LED2

Returns

LED2

function load

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Call type:

function load(filename)

Parameters

filename - [optional] The name of a text JS file to load from Storage after reset

Description

Restart and load the program out of flash - this has an effect similar to completely rebooting Espruino (power off/power on), but without actually performing a full reset of the hardware.

This command only executes when the Interpreter returns to the Idle state - for instance a=1;load();a=2; will still leave 'a' as undefined (or what it was set to in the saved program).

Espruino will resume from where it was when you last typed save(). If you want code to be executed right after loading (for instance to initialise devices connected to Espruino), add an init event handler to E with

E.on('init',
function() { ... your_code ... });
. This will then be automatically executed by Espruino every time it starts.

If you specify a filename in the argument then that file will be loaded from Storage after reset in much the same way as calling reset() then eval(require("Storage").read(filename))

LoopbackA

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Instance of Serial

Description

A loopback serial device. Data sent to LoopbackA comes out of LoopbackB and vice versa

LoopbackB

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Instance of Serial

Description

A loopback serial device. Data sent to LoopbackA comes out of LoopbackB and vice versa

variable LOW

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Call type:

variable LOW

Returns

Logic 0 for Arduino compatibility - this is the same as just typing 0

variable NaN

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Call type:

variable NaN

Returns

Not a Number

function parseFloat

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Call type:

function parseFloat(string)

Parameters

string -

Returns

The value of the string

Description

Convert a string representing a number into an float

function parseInt

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Call type:

function parseInt(string, radix)

Parameters

string -

radix - [optional] The Radix of the string

Returns

The integer value of the string (or NaN)

Description

Convert a string representing a number into an integer

function peek16

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Call type:

function peek16(addr, count)

Parameters

addr - The address in memory to read

count - [optional] the number of items to read. If >1 a Uint16Array will be returned.

Returns

The value of memory at the given location

Description

Read 16 bits of memory at the given location - DANGEROUS!

function peek32

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Call type:

function peek32(addr, count)

Parameters

addr - The address in memory to read

count - [optional] the number of items to read. If >1 a Uint32Array will be returned.

Returns

The value of memory at the given location

Description

Read 32 bits of memory at the given location - DANGEROUS!

function peek8

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Call type:

function peek8(addr, count)

Parameters

addr - The address in memory to read

count - [optional] the number of items to read. If >1 a Uint8Array will be returned.

Returns

The value of memory at the given location

Description

Read 8 bits of memory at the given location - DANGEROUS!

function pinMode

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Call type:

function pinMode(pin, mode, automatic)

Parameters

pin - The pin to set pin mode for

mode - The mode - a string that is either 'analog', 'input', 'inputpullup', 'inputpulldown', 'output', 'opendrain', 'afoutput' or 'afopendrain'. Do not include this argument or use 'auto' if you want to revert to automatic pin mode setting.

automatic - Optional, default is false. If true, subsequent commands will automatically change the state (see notes below)

Description

Set the mode of the given pin.

  • auto/undefined - Don't change state, but allow digitalWrite/etc to automatically change state as appropriate
  • analog - Analog input
  • input - Digital input
  • input_pullup - Digital input with internal ~40k pull-up resistor
  • input_pulldown - Digital input with internal ~40k pull-down resistor
  • output - Digital output
  • opendrain - Digital output that only ever pulls down to 0v. Sending a logical 1 leaves the pin open circuit
  • opendrain_pullup - Digital output that pulls down to 0v. Sending a logical 1 enables internal ~40k pull-up resistor
  • af_output - Digital output from built-in peripheral
  • af_opendrain - Digital output from built-in peripheral that only ever pulls down to 0v. Sending a logical 1 leaves the pin open circuit

    Note: digitalRead/digitalWrite/etc set the pin mode automatically unless pinMode has been called first. If you want digitalRead/etc to set the pin mode automatically after you have called pinMode, simply call it again with no mode argument (pinMode(pin)), auto as the argument (

    pinMode(pin,
    "auto")
    ), or with the 3rd 'automatic' argument set to true (
    pinMode(pin,
    "output", true)
    ).

function poke16

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Call type:

function poke16(addr, value)

Parameters

addr - The address in memory to write

value - The value to write, or an array of values

Description

Write 16 bits of memory at the given location - VERY DANGEROUS!

function poke32

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Call type:

function poke32(addr, value)

Parameters

addr - The address in memory to write

value - The value to write, or an array of values

Description

Write 32 bits of memory at the given location - VERY DANGEROUS!

function poke8

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Call type:

function poke8(addr, value)

Parameters

addr - The address in memory to write

value - The value to write, or an array of values

Description

Write 8 bits of memory at the given location - VERY DANGEROUS!

function print

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Call type:

function print(text, ...)

Parameters

text, ... -

Description

Print the supplied string(s) to the console

Note:* If you're connected to a computer (not a wall adaptor) via USB but *you are not running a terminal app then when you print data Espruino may pause execution and wait until the computer requests the data it is trying to print.

function require

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Call type:

function require(moduleName)

Parameters

moduleName - A String containing the name of the given module

Returns

The result of evaluating the string

Description

Load the given module, and return the exported functions and variables.

For example:


var s = require("Storage");
s.write("test", "hello world");
print(s.read("test"));
// prints "hello world"

Check out the page on Modules for an explanation of what modules are and how you can use them.

function reset

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Call type:

function reset(clearFlash)

Parameters

clearFlash - Remove saved code from flash as well

Description

Reset the interpreter - clear program memory in RAM, and do not load a saved program from flash. This does NOT reset the underlying hardware (which allows you to reset the device without it disconnecting from USB).

This command only executes when the Interpreter returns to the Idle state - for instance a=1;reset();a=2; will still leave 'a' as undefined.

The safest way to do a full reset is to hit the reset button.

If reset() is called with no arguments, it will reset the board's state in RAM but will not reset the state in flash. When next powered on (or when load() is called) the board will load the previously saved code.

Calling reset(true) will cause all saved code in flash memory to be cleared as well.

function save

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Call type:

function save()

Description

Save the state of the interpreter into flash (including the results of calling setWatch, setInterval, pinMode, and any listeners). The state will then be loaded automatically every time Espruino powers on or is hard-reset. To see what will get saved you can call dump().

Note: If you set up intervals/etc in onInit() and you have already called onInit before running save(), when Espruino resumes there will be two copies of your intervals - the ones from before the save, and the ones from after - which may cause you problems.

For more information about this and other options for saving, please see the Saving code on Espruino page.

This command only executes when the Interpreter returns to the Idle state - for instance a=1;save();a=2; will save 'a' as 2.

When Espruino powers on, it will resume from where it was when you typed save(). If you want code to be executed right after loading (for instance to initialise devices connected to Espruino), add a function called onInit, or add a init event handler to E with

E.on('init', function() { ... your_code
... });
. This will then be automatically executed by Espruino every time it starts.

In order to stop the program saved with this command being loaded automatically, check out the Troubleshooting guide

Note: This is not available in Bangle.js smartwatches

Serial1

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Instance of Serial

Description

The first Serial (USART) port

Note: This is only available in devices with more than 1 ESPR_USART peripherals

Serial2

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Instance of Serial

Description

The second Serial (USART) port

Note: This is only available in devices with more than 2 ESPR_USART peripherals

Serial3

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Instance of Serial

Description

The third Serial (USART) port

Note: This is only available in devices with more than 3 ESPR_USART peripherals

Serial4

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Instance of Serial

Description

The fourth Serial (USART) port

Note: This is only available in devices with more than 4 ESPR_USART peripherals

Serial5

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Instance of Serial

Description

The fifth Serial (USART) port

Note: This is only available in devices with more than 5 ESPR_USART peripherals

Serial6

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Instance of Serial

Description

The sixth Serial (USART) port

Note: This is only available in devices with more than 6 ESPR_USART peripherals

function setBusyIndicator

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Call type:

function setBusyIndicator(pin)

Parameters

pin -

Description

When Espruino is busy, set the pin specified here high. Set this to undefined to disable the feature.

Note: This is not available in devices with low flash memory

function setDeepSleep

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Call type:

function setDeepSleep(sleep)

Parameters

sleep -

Description

Set whether we can enter deep sleep mode, which reduces power consumption to around 100uA. This only works on STM32 Espruino Boards (nRF52 boards sleep automatically).

Please see http://www.espruino.com/Power+Consumption for more details on this.

Note: This is only available in STM32 devices (including Espruino Original, Pico and WiFi) and EFM32 devices

function setInterval

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Call type:

function setInterval(function, timeout, args, ...)

Parameters

function - A Function or String to be executed

timeout - The time between calls to the function (max 3153600000000 = 100 years

args, ... - Optional arguments to pass to the function when executed

Returns

An ID that can be passed to clearInterval

Description

Call the function (or evaluate the string) specified REPEATEDLY after the timeout in milliseconds.

For instance:


setInterval(function () {
  console.log("Hello World");
}, 1000);
// or
setInterval('console.log("Hello World");', 1000);
// both print 'Hello World' every second

You can also specify extra arguments that will be sent to the function when it is executed. For example:


setInterval(function (a,b) {
  console.log(a+" "+b);
}, 1000, "Hello", "World");
// prints 'Hello World' every second

If you want to stop your function from being called, pass the number that was returned by setInterval into the clearInterval function.

Note: If setDeepSleep(true) has been called and the interval is greater than 5 seconds, Espruino may execute the interval up to 1 second late. This is because Espruino can only wake from deep sleep every second - and waking early would cause Espruino to waste power while it waited for the correct time.

function setSleepIndicator

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Call type:

function setSleepIndicator(pin)

Parameters

pin -

Description

When Espruino is asleep, set the pin specified here low (when it's awake, set it high). Set this to undefined to disable the feature.

Please see http://www.espruino.com/Power+Consumption for more details on this.

Note: This is not available in devices with low flash memory

function setTime

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Call type:

function setTime(time)

Parameters

time -

Description

Set the current system time in seconds (time can be a floating point value).

This is used with getTime, the time reported from setWatch, as well as when using new Date().

Date.prototype.getTime() reports the time in milliseconds, so you can set the time to a Date object using:


setTime((new Date("Tue, 19 Feb 2019 10:57")).getTime()/1000)

To set the timezone for all new Dates, use E.setTimeZone(hours).

function setTimeout

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Call type:

function setTimeout(function, timeout, args, ...)

Parameters

function - A Function or String to be executed

timeout - The time until the function will be executed (max 3153600000000 = 100 years

args, ... - Optional arguments to pass to the function when executed

Returns

An ID that can be passed to clearTimeout

Description

Call the function (or evaluate the string) specified ONCE after the timeout in milliseconds.

For instance:


setTimeout(function () {
  console.log("Hello World");
}, 1000);
// or
setTimeout('console.log("Hello World");', 1000);
// both print 'Hello World' after a second

You can also specify extra arguments that will be sent to the function when it is executed. For example:


setTimeout(function (a,b) {
  console.log(a+" "+b);
}, 1000, "Hello", "World");
// prints 'Hello World' after 1 second

If you want to stop the function from being called, pass the number that was returned by setTimeout into the clearTimeout function.

Note: If setDeepSleep(true) has been called and the interval is greater than 5 seconds, Espruino may execute the interval up to 1 second late. This is because Espruino can only wake from deep sleep every second - and waking early would cause Espruino to waste power while it waited for the correct time.

function setWatch

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Call type:

function setWatch(function, pin, options)

Parameters

function - A Function or String to be executed

pin - The pin to watch

options - If a boolean or integer, it determines whether to call this once (false = default) or every time a change occurs (true). Can be an object of the form { repeat: true/false(default), edge:'rising'/'falling'/'both', debounce:10} - see below for more information.

Returns

An ID that can be passed to clearWatch

Description

Call the function specified when the pin changes. Watches set with setWatch can be removed using clearWatch.

If the options parameter is an object, it can contain the following information (all optional):


{
   // Whether to keep producing callbacks, or remove the watch after the first callback
   repeat: true/false(default),
   // Trigger on the rising or falling edge of the signal. Can be a string, or 1='rising', -1='falling', 0='both'
   edge:'rising'(default for built-in buttons)/'falling'/'both'(default for pins),
   // Use software-debouncing to stop multiple calls if a switch bounces
   // This is the time in milliseconds to wait for bounces to subside, or 0 to disable
   debounce:10 (0 is default for pins, 25 is default for built-in buttons),
   // Advanced: If the function supplied is a 'native' function (compiled or assembly)
   // setting irq:true will call that function in the interrupt itself
   irq : false(default)
   // Advanced: If specified, the given pin will be read whenever the watch is called
   // and the state will be included as a 'data' field in the callback (`debounce:0` is required)
   data : pin
   // Advanced: On Nordic devices, a watch may be 'high' or 'low' accuracy. By default low
   // accuracy is used (which is better for power consumption), but this means that
   // high speed pulses (less than 25us) may not be reliably received. Setting hispeed=true
   // allows for detecting high speed pulses at the expense of higher idle power consumption
   hispeed : true
}

The function callback is called with an argument, which is an object of type {state:bool, time:float, lastTime:float}.

  • state is whether the pin is currently a 1 or a 0
  • time is the time in seconds at which the pin changed state
  • lastTime is the time in seconds at which the pin last changed state. When using edge:'rising' or edge:'falling', this is not the same as when the function was last called.
  • data is included if data:pin was specified in the options, and can be used for reading in clocked data. It will only work if debounce:0 is used

For instance, if you want to measure the length of a positive pulse you could use

setWatch(function(e) { console.log(e.time-e.lastTime); }, BTN, {
repeat:true, edge:'falling' });
. This will only be called on the falling edge of the pulse, but will be able to measure the width of the pulse because e.lastTime is the time of the rising edge.

Internally, an interrupt writes the time of the pin's state change into a queue with the exact time that it happened, and the function supplied to setWatch is executed only from the main message loop. However, if the callback is a native function void (bool state) then you can add irq:true to options, which will cause the function to be called from within the IRQ. When doing this, interrupts will happen on both edges and there will be no debouncing.

Note: if you didn't call pinMode beforehand then this function will reset pin's state to "input"

Note: The STM32 chip (used in the Espruino Board and Pico) cannot watch two pins with the same number - e.g. A0 and B0.

Note: On nRF52 chips (used in Puck.js, Pixl.js, MDBT42Q) setWatch disables the GPIO output on that pin. In order to be able to write to the pin again you need to disable the watch with clearWatch.

function shiftOut

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Call type:

function shiftOut(pins, options, data)

Parameters

pins - A pin, or an array of pins to use

options - Options, for instance the clock (see below)

data - The data to shift out (see E.toUint8Array for info on the forms this can take)

Description

Shift an array of data out using the pins supplied least significant bit first, for example:


// shift out to single clk+data
shiftOut(A0, { clk : A1 }, [1,0,1,0]);


// shift out a whole byte (like software SPI)
shiftOut(A0, { clk : A1, repeat: 8 }, [1,2,3,4]);


// shift out via 4 data pins
shiftOut([A3,A2,A1,A0], { clk : A4 }, [1,2,3,4]);

options is an object of the form:


{
  clk : pin, // a pin to use as the clock (undefined = no pin)
  clkPol : bool, // clock polarity - default is 0 (so 1 normally, pulsing to 0 to clock data in)
  repeat : int, // number of clocks per array item
}

Each item in the data array will be output to the pins, with the first pin in the array being the MSB and the last the LSB, then the clock will be pulsed in the polarity given.

repeat is the amount of times shift data out for each array item. For instance we may want to shift 8 bits out through 2 pins - in which case we need to set repeat to 4.

SPI1

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Instance of SPI

Description

The first SPI port

Note: This is only available in devices with more than 1 ESPR_SPI peripherals

SPI2

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Instance of SPI

Description

The second SPI port

Note: This is only available in devices with more than 2 ESPR_SPI peripherals

SPI3

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Instance of SPI

Description

The third SPI port

Note: This is only available in devices with more than 3 ESPR_SPI peripherals

function trace

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Call type:

function trace(root)

Parameters

root - The symbol to output (optional). If nothing is specified, everything will be output

Description

Output debugging information

Note: This is not included on boards with low amounts of flash memory, or the Espruino board.

Note: This is not available in devices with low flash memory

USB

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Instance of Serial

Description

The USB Serial port

Note: This is only available in devices with USB

AES Class

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Class containing AES encryption/decryption

Note: This library is currently only included in builds for boards where there is space. For other boards there is crypto.js which implements SHA1 in JS.

Methods and Fields

AES.decrypt

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Call type:

AES.decrypt(passphrase, key, options)

Parameters

passphrase - Message to decrypt

key - Key to encrypt message - must be an ArrayBuffer of 128, 192, or 256 BITS

options - [optional] An object, may specify { iv : new Uint8Array(16), mode : 'CBC|CFB|CTR|OFB|ECB' }

Returns

Returns an ArrayBuffer

AES.encrypt

(top)

Call type:

AES.encrypt(passphrase, key, options)

Parameters

passphrase - Message to encrypt

key - Key to encrypt message - must be an ArrayBuffer of 128, 192, or 256 BITS

options - [optional] An object, may specify { iv : new Uint8Array(16), mode : 'CBC|CFB|CTR|OFB|ECB' }

Returns

Returns an ArrayBuffer

Array Class

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This is the built-in JavaScript class for arrays.

Arrays can be defined with [], new Array(), or

new
Array(length)

Methods and Fields

constructor Array

View MDN documentation

(top)

Call type:

new Array(args, ...)

Parameters

args, ... - The length of the array OR any number of items to add to the array

Returns

An Array

Description

Create an Array. Either give it one integer argument (>=0) which is the length of the array, or any number of arguments

function Array.concat

View MDN documentation

(top)

Call type:

function Array.concat(args, ...)

Parameters

args, ... - Any items to add to the array

Returns

An Array

Description

Create a new array, containing the elements from this one and any arguments, if any argument is an array then those elements will be added.

Note: This is not available in devices with low flash memory

function Array.every

View MDN documentation

(top)

Call type:

function Array.every(function, thisArg)

Parameters

function - Function to be executed

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Returns

A boolean containing the result

Description

Return 'true' if the callback returns 'true' for every element in the array

function Array.fill

View MDN documentation

(top)

Call type:

function Array.fill(value, start, end)

Parameters

value - The value to fill the array with

start - Optional. The index to start from (or 0). If start is negative, it is treated as length+start where length is the length of the array

end - Optional. The index to end at (or the array length). If end is negative, it is treated as length+end.

Returns

This array

Description

Fill this array with the given value, for every index >= start and < end

Note: This is not available in devices with low flash memory

function Array.filter

View MDN documentation

(top)

Call type:

function Array.filter(function, thisArg)

Parameters

function - Function to be executed

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Returns

An array containing the results

Description

Return an array which contains only those elements for which the callback function returns 'true'

function Array.find

View MDN documentation

(top)

Call type:

function Array.find(function)

Parameters

function - Function to be executed

Returns

The array element where function returns true, or undefined

Description

Return the array element where function returns true, or undefined if it doesn't returns true for any element.


["Hello","There","World"].find(a=>a[0]=="T")
// returns "There"

Note: This is not available in devices with low flash memory

function Array.findIndex

View MDN documentation

(top)

Call type:

function Array.findIndex(function)

Parameters

function - Function to be executed

Returns

The array element's index where function returns true, or -1

Description

Return the array element's index where function returns true, or -1 if it doesn't returns true for any element.


["Hello","There","World"].findIndex(a=>a[0]=="T")
// returns 1

Note: This is not available in devices with low flash memory

function Array.forEach

View MDN documentation

(top)

Call type:

function Array.forEach(function, thisArg)

Parameters

function - Function to be executed

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Description

Executes a provided function once per array element.

function Array.includes

View MDN documentation

(top)

Call type:

function Array.includes(value, startIndex)

Parameters

value - The value to check for

startIndex - [optional] the index to search from, or 0 if not specified

Returns

true if the array includes the value, false otherwise

Description

Return true if the array includes the value, false otherwise

Note: This is not available in devices with low flash memory

function Array.indexOf

View MDN documentation

(top)

Call type:

function Array.indexOf(value, startIndex)

Parameters

value - The value to check for

startIndex - [optional] the index to search from, or 0 if not specified

Returns

the index of the value in the array, or -1

Description

Return the index of the value in the array, or -1

Array.isArray

View MDN documentation

(top)

Call type:

Array.isArray(var)

Parameters

var - The variable to be tested

Returns

True if var is an array, false if not.

Description

Returns true if the provided object is an array

function Array.join

View MDN documentation

(top)

Call type:

function Array.join(separator)

Parameters

separator - The separator

Returns

A String representing the Joined array

Description

Join all elements of this array together into one string, using 'separator' between them. e.g. [1,2,3].join(' ')=='1 2 3'

property Array.length

View MDN documentation

(top)

Call type:

property Array.length

Returns

The length of the array

Description

Find the length of the array

function Array.map

View MDN documentation

(top)

Call type:

function Array.map(function, thisArg)

Parameters

function - Function used to map one item to another

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Returns

An array containing the results

Description

Return an array which is made from the following:

A.map(function) =
[function(A[0]), function(A[1]), ...]

function Array.pop

View MDN documentation

(top)

Call type:

function Array.pop()

Returns

The value that is popped off

Description

Remove and return the value on the end of this array.

This is the opposite of [1,2,3].shift(), which removes an element from the beginning of the array.

function Array.push

View MDN documentation

(top)

Call type:

function Array.push(arguments, ...)

Parameters

arguments, ... - One or more arguments to add

Returns

The new size of the array

Description

Push a new value onto the end of this array'

This is the opposite of [1,2,3].unshift(0), which adds one or more elements to the beginning of the array.

function Array.reduce

View MDN documentation

(top)

Call type:

function Array.reduce(callback, initialValue)

Parameters

callback - Function used to reduce the array

initialValue - if specified, the initial value to pass to the function

Returns

The value returned by the last function called

Description

Execute previousValue=initialValue and then

previousValue =
callback(previousValue, currentValue, index, array)
for each element in the array, and finally return previousValue.

Note: This is not available in devices with low flash memory

function Array.reverse

View MDN documentation

(top)

Call type:

function Array.reverse()

Returns

The array, but reversed.

Description

Reverse all elements in this array (in place)

Note: This is not available in devices with low flash memory

function Array.shift

View MDN documentation

(top)

Call type:

function Array.shift()

Parameters

Returns

The element that was removed

Description

Remove and return the first element of the array.

This is the opposite of [1,2,3].pop(), which takes an element off the end.

Note: This is not available in devices with low flash memory

function Array.slice

View MDN documentation

(top)

Call type:

function Array.slice(start, end)

Parameters

start - Start index

end - [optional] End index

Returns

A new array

Description

Return a copy of a portion of this array (in a new array)

function Array.some

View MDN documentation

(top)

Call type:

function Array.some(function, thisArg)

Parameters

function - Function to be executed

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Returns

A boolean containing the result

Description

Return 'true' if the callback returns 'true' for any of the elements in the array

function Array.sort

View MDN documentation

(top)

Call type:

function Array.sort(var)

Parameters

var - A function to use to compare array elements (or undefined)

Returns

This array object

Description

Do an in-place quicksort of the array

Note: This is not available in devices with low flash memory

function Array.splice

View MDN documentation

(top)

Call type:

function Array.splice(index, howMany, elements, ...)

Parameters

index - Index at which to start changing the array. If negative, will begin that many elements from the end

howMany - An integer indicating the number of old array elements to remove. If howMany is 0, no elements are removed.

elements, ... - One or more items to add to the array

Returns

An array containing the removed elements. If only one element is removed, an array of one element is returned.

Description

Both remove and add items to an array

function Array.toString

View MDN documentation

(top)

Call type:

function Array.toString(radix)

Parameters

radix - unused

Returns

A String representing the array

Description

Convert the Array to a string

function Array.unshift

View MDN documentation

(top)

Call type:

function Array.unshift(elements, ...)

Parameters

elements, ... - One or more items to add to the beginning of the array

Returns

The new array length

Description

Add one or more items to the start of the array, and return its new length.

This is the opposite of [1,2,3].push(4), which puts one or more elements on the end.

Note: This is not available in devices with low flash memory

ArrayBuffer Class

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This is the built-in JavaScript class for array buffers.

If you want to access arrays of differing types of data you may also find DataView useful.

Methods and Fields

constructor ArrayBuffer

View MDN documentation

(top)

Call type:

new ArrayBuffer(byteLength)

Parameters

byteLength - The length in Bytes

Returns

An ArrayBuffer object

Description

Create an Array Buffer object

property ArrayBuffer.byteLength

View MDN documentation

(top)

Call type:

property ArrayBuffer.byteLength

Returns

The Length in bytes

Description

The length, in bytes, of the ArrayBuffer

ArrayBufferView Class

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This is the built-in JavaScript class that is the prototype for:

If you want to access arrays of differing types of data you may also find DataView useful.

Methods and Fields

property ArrayBufferView.buffer

(top)

Call type:

property ArrayBufferView.buffer

Returns

An ArrayBuffer object

Description

The buffer this view references

property ArrayBufferView.byteLength

(top)

Call type:

property ArrayBufferView.byteLength

Returns

The Length

Description

The length, in bytes, of the ArrayBufferView

property ArrayBufferView.byteOffset

(top)

Call type:

property ArrayBufferView.byteOffset

Returns

The byte Offset

Description

The offset, in bytes, to the first byte of the view within the backing ArrayBuffer

function ArrayBufferView.fill

(top)

Call type:

function ArrayBufferView.fill(value, start, end)

Parameters

value - The value to fill the array with

start - Optional. The index to start from (or 0). If start is negative, it is treated as length+start where length is the length of the array

end - Optional. The index to end at (or the array length). If end is negative, it is treated as length+end.

Returns

This array

Description

Fill this array with the given value, for every index >= start and < end

Note: This is not available in devices with low flash memory

function ArrayBufferView.filter

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Call type:

function ArrayBufferView.filter(function, thisArg)

Parameters

function - Function to be executed

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Returns

An array containing the results

Description

Return an array which contains only those elements for which the callback function returns 'true'

Note: This is not available in devices with low flash memory

function ArrayBufferView.find

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Call type:

function ArrayBufferView.find(function)

Parameters

function - Function to be executed

Returns

The array element where function returns true, or undefined

Description

Return the array element where function returns true, or undefined if it doesn't returns true for any element.

Note: This is not available in devices with low flash memory

function ArrayBufferView.findIndex

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Call type:

function ArrayBufferView.findIndex(function)

Parameters

function - Function to be executed

Returns

The array element's index where function returns true, or -1

Description

Return the array element's index where function returns true, or -1 if it doesn't returns true for any element.

Note: This is not available in devices with low flash memory

function ArrayBufferView.forEach

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Call type:

function ArrayBufferView.forEach(function, thisArg)

Parameters

function - Function to be executed

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Description

Executes a provided function once per array element.

function ArrayBufferView.includes

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Call type:

function ArrayBufferView.includes(value, startIndex)

Parameters

value - The value to check for

startIndex - [optional] the index to search from, or 0 if not specified

Returns

true if the array includes the value, false otherwise

Description

Return true if the array includes the value, false otherwise

Note: This is not available in devices with low flash memory

function ArrayBufferView.indexOf

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Call type:

function ArrayBufferView.indexOf(value, startIndex)

Parameters

value - The value to check for

startIndex - [optional] the index to search from, or 0 if not specified

Returns

the index of the value in the array, or -1

Description

Return the index of the value in the array, or -1

function ArrayBufferView.join

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Call type:

function ArrayBufferView.join(separator)

Parameters

separator - The separator

Returns

A String representing the Joined array

Description

Join all elements of this array together into one string, using 'separator' between them. e.g. [1,2,3].join(' ')=='1 2 3'

function ArrayBufferView.map

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Call type:

function ArrayBufferView.map(function, thisArg)

Parameters

function - Function used to map one item to another

thisArg - [optional] If specified, the function is called with 'this' set to thisArg

Returns

An array containing the results

Description

Return an array which is made from the following:

A.map(function) =
[function(A[0]), function(A[1]), ...]

Note: This returns an ArrayBuffer of the same type it was called on. To get an Array, use Array.map, e.g. [].map.call(myArray, x=>x+1)

function ArrayBufferView.reduce

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Call type:

function ArrayBufferView.reduce(callback, initialValue)

Parameters

callback - Function used to reduce the array

initialValue - if specified, the initial value to pass to the function

Returns

The value returned by the last function called

Description

Execute previousValue=initialValue and then

previousValue =
callback(previousValue, currentValue, index, array)
for each element in the array, and finally return previousValue.

Note: This is not available in devices with low flash memory

function ArrayBufferView.reverse

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Call type:

function ArrayBufferView.reverse()

Returns

This array

Description

Reverse the contents of this ArrayBufferView in-place

Note: This is not available in devices with low flash memory

function ArrayBufferView.set

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Call type:

function ArrayBufferView.set(arr, offset)

Parameters

arr - Floating point index to access

offset - [optional] The offset in this array at which to write the values

Description

Copy the contents of array into this one, mapping this[x+offset]=array[x];

function ArrayBufferView.slice

(top)

Call type:

function ArrayBufferView.slice(start, end)

Parameters

start - Start index

end - [optional] End index

Returns

A new array

Description

Return a copy of a portion of this array (in a new array).

Note: This currently returns a normal Array, not an ArrayBuffer

Note: This is not available in devices with low flash memory

function ArrayBufferView.sort

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Call type:

function ArrayBufferView.sort(var)

Parameters

var - A function to use to compare array elements (or undefined)

Returns

This array object

Description

Do an in-place quicksort of the array

Note: This is not available in devices with low flash memory

function ArrayBufferView.subarray

(top)

Call type:

function ArrayBufferView.subarray(begin, end)

Parameters

begin - Element to begin at, inclusive. If negative, this is from the end of the array. The entire array is included if this isn't specified

end - Element to end at, exclusive. If negative, it is relative to the end of the array. If not specified the whole array is included

Returns

An ArrayBufferView of the same type as this one, referencing the same data

Description

Returns a smaller part of this array which references the same data (it doesn't copy it).

Note: This is not available in devices with low flash memory

Boolean Class

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Methods and Fields

constructor Boolean

View MDN documentation

(top)

Call type:

new Boolean(value)

Parameters

value - A single value to be converted to a number

Returns

A Boolean object

Description

Creates a boolean

console Class

(top)

An Object that contains functions for writing to the interactive console

Methods and Fields

console.debug

(top)

Call type:

console.debug(text, ...)

Parameters

text, ... - One or more arguments to print

Description

Implemented in Espruino as an alias of console.log

console.error

(top)

Call type:

console.error(text, ...)

Parameters

text, ... - One or more arguments to print

Description

Implemented in Espruino as an alias of console.log

console.info

(top)

Call type:

console.info(text, ...)

Parameters

text, ... - One or more arguments to print

Description

Implemented in Espruino as an alias of console.log

console.log

(top)

Call type:

console.log(text, ...)

Parameters

text, ... - One or more arguments to print

Description

Print the supplied string(s) to the console

Note:* If you're connected to a computer (not a wall adaptor) via USB but *you are not running a terminal app then when you print data Espruino may pause execution and wait until the computer requests the data it is trying to print.

console.warn

(top)

Call type:

console.warn(text, ...)

Parameters

text, ... - One or more arguments to print

Description

Implemented in Espruino as an alias of console.log

crypto Library

(top)

Cryptographic functions

Note: This library is currently only included in builds for boards where there is space. For other boards there is crypto.js which implements SHA1 in JS.

Methods and Fields

crypto.AES

(top)

Call type:

require("crypto").AES

Returns

See description above

Description

Class containing AES encryption/decryption

Note: This is only available in devices that support AES (Espruino Pico, Espruino WiFi or Linux)

crypto.PBKDF2

(top)

Call type:

require("crypto").PBKDF2(passphrase, salt, options)

Parameters

passphrase - Passphrase

salt - Salt for turning passphrase into a key

options - Object of Options, { keySize: 8 (in 32 bit words), iterations: 10, hasher: 'SHA1'/'SHA224'/'SHA256'/'SHA384'/'SHA512' }

Returns

Returns an ArrayBuffer

Description

Password-Based Key Derivation Function 2 algorithm, using SHA512

Note: This is only available in devices with TLS and SSL support (Espruino Pico and Espruino WiFi only)

crypto.SHA1

(top)

Call type:

require("crypto").SHA1(message)

Parameters

message - The message to apply the hash to

Returns

Returns a 20 byte ArrayBuffer

Description

Performs a SHA1 hash and returns the result as a 20 byte ArrayBuffer.

Note: On some boards (currently only Espruino Original) there isn't space for a fully unrolled SHA1 implementation so a slower all-JS implementation is used instead.

Note: This is only available in devices that support Crypto Functionality (Espruino Pico, Original, Espruino WiFi, Espruino BLE devices, Linux or ESP8266)

crypto.SHA224

(top)

Call type:

require("crypto").SHA224(message)

Parameters

message - The message to apply the hash to

Returns

Returns a 20 byte ArrayBuffer

Description

Performs a SHA224 hash and returns the result as a 28 byte ArrayBuffer

Note: This is only available in devices that support SHA256 (Espruino Pico, Espruino WiFi, Espruino BLE devices or Linux)

crypto.SHA256

(top)

Call type:

require("crypto").SHA256(message)

Parameters

message - The message to apply the hash to

Returns

Returns a 20 byte ArrayBuffer

Description

Performs a SHA256 hash and returns the result as a 32 byte ArrayBuffer

Note: This is only available in devices that support SHA256 (Espruino Pico, Espruino WiFi, Espruino BLE devices or Linux)

crypto.SHA384

(top)

Call type:

require("crypto").SHA384(message)

Parameters

message - The message to apply the hash to

Returns

Returns a 20 byte ArrayBuffer

Description

Performs a SHA384 hash and returns the result as a 48 byte ArrayBuffer

Note: This is only available in devices that support SHA512 (Espruino Pico, Espruino WiFi, Espruino BLE devices or Linux)

crypto.SHA512

(top)

Call type:

require("crypto").SHA512(message)

Parameters

message - The message to apply the hash to

Returns

Returns a 32 byte ArrayBuffer

Description

Performs a SHA512 hash and returns the result as a 64 byte ArrayBuffer

Note: This is only available in devices that support SHA512 (Espruino Pico, Espruino WiFi, Espruino BLE devices or Linux)

DataView Class

(top)

This class helps

Methods and Fields

constructor DataView

View MDN documentation

(top)

Call type:

new DataView(buffer, byteOffset, byteLength)

Parameters

buffer - The ArrayBuffer to base this on

byteOffset - [optional] The offset of this view in bytes

byteLength - [optional] The length in bytes

Returns

A DataView object

Description

Create a DataView object that can be used to access the data in an ArrayBuffer.


var b = new ArrayBuffer(8)
var v = new DataView(b)
v.setUint16(0,"0x1234")
v.setUint8(3,"0x56")
console.log("0x"+v.getUint32(0).toString(16))
// prints 0x12340056

Note: This is not available in devices with low flash memory

function DataView.getFloat32

View MDN documentation

(top)

Call type:

function DataView.getFloat32(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getFloat64

View MDN documentation

(top)

Call type:

function DataView.getFloat64(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getInt16

View MDN documentation

(top)

Call type:

function DataView.getInt16(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getInt32

View MDN documentation

(top)

Call type:

function DataView.getInt32(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getInt8

View MDN documentation

(top)

Call type:

function DataView.getInt8(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getUint16

View MDN documentation

(top)

Call type:

function DataView.getUint16(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getUint32

View MDN documentation

(top)

Call type:

function DataView.getUint32(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.getUint8

View MDN documentation

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Call type:

function DataView.getUint8(byteOffset, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Returns

the index of the value in the array, or -1

function DataView.setFloat32

View MDN documentation

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Call type:

function DataView.setFloat32(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setFloat64

View MDN documentation

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Call type:

function DataView.setFloat64(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setInt16

View MDN documentation

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Call type:

function DataView.setInt16(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setInt32

View MDN documentation

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Call type:

function DataView.setInt32(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setInt8

View MDN documentation

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Call type:

function DataView.setInt8(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setUint16

View MDN documentation

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Call type:

function DataView.setUint16(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setUint32

View MDN documentation

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Call type:

function DataView.setUint32(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

function DataView.setUint8

View MDN documentation

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Call type:

function DataView.setUint8(byteOffset, value, littleEndian)

Parameters

byteOffset - The offset in bytes to read from

value - The value to write

littleEndian - [optional] Whether to read in little endian - if false or undefined data is read as big endian

Date Class

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The built-in class for handling Dates.

Note: By default the time zone is GMT+0, however you can change the timezone using the E.setTimeZone(...) function.

For example E.setTimeZone(1) will be GMT+0100

However if you have daylight savings time set with E.setDST(...) then the timezone set by E.setTimeZone(...) will be ignored.

Methods and Fields

constructor Date

View MDN documentation

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Call type:

new Date(args, ...)

Parameters

args, ... - Either nothing (current time), one numeric argument (milliseconds since 1970), a date string (see Date.parse), or [year, month, day, hour, minute, second, millisecond]

Returns

A Date object

Description

Creates a date object

function Date.getDate

View MDN documentation

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Call type:

function Date.getDate()

Returns

See description above

Description

Day of the month 1..31

function Date.getDay

View MDN documentation

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Call type:

function Date.getDay()

Returns

See description above

Description

Day of the week (0=sunday, 1=monday, etc)

function Date.getFullYear

View MDN documentation

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Call type:

function Date.getFullYear()

Returns

See description above

Description

The year, e.g. 2014

function Date.getHours

View MDN documentation

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Call type:

function Date.getHours()

Returns

See description above

Description

0..23

function Date.getIsDST

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Call type:

function Date.getIsDST()

Returns

true if daylight savings time is in effect

Description

This returns a boolean indicating whether daylight savings time is in effect.

Note: This is not available in devices with low flash memory

function Date.getMilliseconds

View MDN documentation

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Call type:

function Date.getMilliseconds()

Returns

See description above

Description

0..999

function Date.getMinutes

View MDN documentation

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Call type:

function Date.getMinutes()

Returns

See description above

Description

0..59

function Date.getMonth

View MDN documentation

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Call type:

function Date.getMonth()

Returns

See description above

Description

Month of the year 0..11

function Date.getSeconds

View MDN documentation

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Call type:

function Date.getSeconds()

Returns

See description above

Description

0..59

function Date.getTime

View MDN documentation

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Call type:

function Date.getTime()

Returns

See description above

Description

Return the number of milliseconds since 1970

function Date.getTimezoneOffset

View MDN documentation

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Call type:

function Date.getTimezoneOffset()

Returns

The difference, in minutes, between UTC and local time

Description

This returns the time-zone offset from UTC, in minutes.

Note: This is not available in devices with low flash memory

Date.now

View MDN documentation

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Call type:

Date.now()

Returns

See description above

Description

Get the number of milliseconds elapsed since 1970 (or on embedded platforms, since startup).

Note: Desktop JS engines return an integer value for Date.now(), however Espruino returns a floating point value, accurate to fractions of a millisecond.

Date.parse

View MDN documentation

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Call type:

Date.parse(str)

Parameters

str - A String

Returns

The number of milliseconds since 1970

Description

Parse a date string and return milliseconds since 1970. Data can be either '2011-10-20T14:48:00', '2011-10-20' or 'Mon, 25 Dec 1995 13:30:00 +0430'

function Date.setDate

View MDN documentation

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Call type:

function Date.setDate(dayValue)

Parameters

dayValue - the day of the month, between 0 and 31

Returns

The number of milliseconds since 1970

Description

Day of the month 1..31

Note: This is not available in devices with low flash memory

function Date.setFullYear

View MDN documentation

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Call type:

function Date.setFullYear(yearValue, monthValue, dayValue)

Parameters

yearValue - The full year - eg. 1989

monthValue - [optional] the month, between 0 and 11

dayValue - [optional] the day, between 0 and 31

Returns

The number of milliseconds since 1970

function Date.setHours

View MDN documentation

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Call type:

function Date.setHours(hoursValue, minutesValue, secondsValue, millisecondsValue)

Parameters

hoursValue - number of hours, 0..23

minutesValue - number of minutes, 0..59

secondsValue - [optional] number of seconds, 0..59

millisecondsValue - [optional] number of milliseconds, 0..999

Returns

The number of milliseconds since 1970

Description

0..23

Note: This is not available in devices with low flash memory

function Date.setMilliseconds

View MDN documentation

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Call type:

function Date.setMilliseconds(millisecondsValue)

Parameters

millisecondsValue - number of milliseconds, 0..999

Returns

The number of milliseconds since 1970

function Date.setMinutes

View MDN documentation

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Call type:

function Date.setMinutes(minutesValue, secondsValue, millisecondsValue)

Parameters

minutesValue - number of minutes, 0..59

secondsValue - [optional] number of seconds, 0..59

millisecondsValue - [optional] number of milliseconds, 0..999

Returns

The number of milliseconds since 1970

Description

0..59

Note: This is not available in devices with low flash memory

function Date.setMonth

View MDN documentation

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Call type:

function Date.setMonth(monthValue, dayValue)

Parameters

monthValue - The month, between 0 and 11

dayValue - [optional] the day, between 0 and 31

Returns

The number of milliseconds since 1970

Description

Month of the year 0..11

Note: This is not available in devices with low flash memory

function Date.setSeconds

View MDN documentation

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Call type:

function Date.setSeconds(secondsValue, millisecondsValue)

Parameters

secondsValue - number of seconds, 0..59

millisecondsValue - [optional] number of milliseconds, 0..999

Returns

The number of milliseconds since 1970

Description

0..59

Note: This is not available in devices with low flash memory

function Date.setTime

View MDN documentation

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Call type:

function Date.setTime(timeValue)

Parameters

timeValue - the number of milliseconds since 1970

Returns

the number of milliseconds since 1970

Description

Set the time/date of this Date class

function Date.toISOString

View MDN documentation

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Call type:

function Date.toISOString()

Returns

A String

Description

Converts to a ISO 8601 String, e.g: 2014-06-20T14:52:20.123Z

Note: This always assumes a timezone of GMT

function Date.toJSON

View MDN documentation

(top)

Call type:

function Date.toJSON()

Returns

A String

Description

Calls Date.toISOString to output this date to JSON

function Date.toLocalISOString

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Call type:

function Date.toLocalISOString()

Returns

A String

Description

Converts to a ISO 8601 String (with timezone information), e.g: 2014-06-20T14:52:20.123-0500

Note: This is not available in devices with low flash memory

function Date.toString

View MDN documentation

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Call type:

function Date.toString()

Returns

A String

Description

Converts to a String, e.g: Fri Jun 20 2014 14:52:20 GMT+0000

Note: This uses whatever timezone was set with E.setTimeZone() or E.setDST()

function Date.toUTCString

View MDN documentation

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Call type:

function Date.toUTCString()

Returns

A String

Description

Converts to a String, e.g: Fri, 20 Jun 2014 14:52:20 GMT

Note: This always assumes a timezone of GMT

function Date.valueOf

View MDN documentation

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Call type:

function Date.valueOf()

Returns

See description above

Description

Return the number of milliseconds since 1970

dgram Library

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This library allows you to create UDP/DATAGRAM servers and clients

In order to use this, you will need an extra module to get network connectivity.

This is designed to be a cut-down version of the node.js library. Please see the Internet page for more information on how to use it.

Methods and Fields

dgram.createSocket

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Call type:

require("dgram").createSocket(type, callback)

Parameters

type - Socket type to create e.g. 'udp4'. Or options object { type: 'udp4', reuseAddr: true, recvBufferSize: 1024 }

callback - A function(sckt) that will be called with the socket when a connection is made. You can then call sckt.send(...) to send data, and sckt.on('message', function(data) { ... }) and sckt.on('close', function() { ... }) to deal with the response.

Returns

Returns a new dgram.Socket object

Description

Create a UDP socket

dgramSocket Class

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An actual socket connection - allowing transmit/receive of TCP data

Methods and Fields

function dgramSocket.addMembership

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Call type:

function dgramSocket.addMembership(group, ip)

Parameters

group - A string containing the group ip to join

ip - A string containing the ip to join with

function dgramSocket.bind

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Call type:

function dgramSocket.bind(port, callback)

Parameters

port - The port to bind at

callback - A function(res) that will be called when the socket is bound. You can then call res.on('message', function(message, info) { ... }) and res.on('close', function() { ... }) to deal with the response.

Returns

The dgramSocket instance that 'bind' was called on

function dgramSocket.close

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Call type:

function dgramSocket.close()

Description

Close the socket

event dgramSocket.close

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Call type:

dgramSocket.on('close', function(had_error) { ... });

Parameters

had_error - A boolean indicating whether the connection had an error (use an error event handler to get error details).

Description

Called when the connection closes.

event dgramSocket.message

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Call type:

dgramSocket.on('message', function(msg, rinfo) { ... });

Parameters

msg - A string containing the received message

rinfo - Sender address,port containing information

Description

The 'message' event is called when a datagram message is received. If a handler is defined with X.on('message', function(msg) { ... }) then it will be called`

function dgramSocket.send

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Call type:

function dgramSocket.send(buffer, offset, length, args, ...)

Parameters

buffer - A string containing message to send

offset - Offset in the passed string where the message starts [optional]

length - Number of bytes in the message [optional]

args, ... - Destination port number, Destination IP address string

E Class

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This is the built-in JavaScript class for Espruino utility functions.

Methods and Fields

E.asm

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Call type:

E.asm(callspec, assemblycode, ...)

Parameters

callspec - The arguments this assembly takes - e.g. void(int)

assemblycode, ... - One of more strings of assembler code

Description

Provide assembly to Espruino.

This function is not part of Espruino. Instead, it is detected by the Espruino IDE (or command-line tools) at upload time and is replaced with machine code and an E.nativeCall call.

See the documentation on the Assembler for more information.

Note: This is not available in devices with low flash memory

E.asUTF8

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Call type:

E.asUTF8(str)

Parameters

str - The string to turn into a UTF8 Unicode String

Returns

A String

Description

By default, strings in Espruino are standard 8 bit binary strings unless they contain Unicode chars or a \u#### escape code that doesn't map to the range 0..255.

However calling E.asUTF8 will convert one of those strings to UTF8.


var s = String.fromCharCode(0xF0,0x9F,0x8D,0x94);
var u = E.asUTF8(s);
s.length // 4
s[0] // "\xF0"
u.length // 1
u[0] // hamburger emoji

NOTE: UTF8 is currently only available on Bangle.js devices

Note: This is not available in devices with low flash memory

E.clip

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Call type:

E.clip(x, min, max)

Parameters

x - A floating point value to clip

min - The smallest the value should be

max - The largest the value should be

Returns

The value of x, clipped so as not to be below min or above max.

Description

Clip a number to be between min and max (inclusive)

Note: This is not available in devices with low flash memory

E.compiledC

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Call type:

E.compiledC(code)

Parameters

code - A Templated string of C code

Description

Provides the ability to write C code inside your JavaScript file.

This function is not part of Espruino. Instead, it is detected by the Espruino IDE (or command-line tools) at upload time, is sent to our web service to be compiled, and is replaced with machine code and an E.nativeCall call.

See the documentation on Inline C for more information and examples.

Note: This is not available in devices with low flash memory

E.connectSDCard

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Call type:

E.connectSDCard(spi, csPin)

Parameters

spi - The SPI object to use for communication

csPin - The pin to use for Chip Select

Description

Setup the filesystem so that subsequent calls to E.openFile and require('fs').* will use an SD card on the supplied SPI device and pin.

It can even work using software SPI - for instance:


// DI/CMD = C7
// DO/DAT0 = C8
// CK/CLK = C9
// CD/CS/DAT3 = C6
var spi = new SPI();
spi.setup({mosi:C7, miso:C8, sck:C9});
E.connectSDCard(spi, C6);
console.log(require("fs").readdirSync());

See the page on File IO for more information.

Note: We'd strongly suggest you add a pullup resistor from CD/CS pin to 3.3v. It is good practise to avoid accidental writes before Espruino is initialised, and some cards will not work reliably without one.

Note: If you want to remove an SD card after you have started using it, you must call E.unmountSD() or you may cause damage to the card.

Note: This is not available in devices with low flash memory

E.convolve

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Call type:

E.convolve(arr1, arr2, offset)

Parameters

arr1 - An array to convolve

arr2 - An array to convolve

offset - The mean value of the array

Returns

The variance of the given buffer

Description

Convolve arr1 with arr2. This is equivalent to

v=0;for (i in arr1) v+=arr1[i] *
arr2[(i+offset) % arr2.length]

Note: This is not available in devices with low flash memory

E.CRC32

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Call type:

E.CRC32(data)

Parameters

data - Iterable data to perform CRC32 on (each element treated as a byte)

Returns

The CRC of the supplied data

Description

Perform a standard 32 bit CRC (Cyclic redundancy check) on the supplied data (one byte at a time) and return the result as an unsigned integer.

Note: This is not available in devices with low flash memory

E.decodeUTF8

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Call type:

E.decodeUTF8(str, lookup, replaceFn)

Parameters

str - A string of UTF8-encoded data

lookup - An array containing a mapping of character code -> replacement string

replaceFn - If not in lookup, replaceFn(charCode) is called and the result used if it's a function, or if it's a string, the string value is used

Returns

A string containing all UTF8 sequences flattened to 8 bits

Description

Decode a UTF8 string.

  • Any decoded character less than 256 gets passed straight through
  • Otherwise if lookup is an array and an item with that char code exists in lookup then that is used
  • Otherwise if lookup is an object and an item with that char code (as lowercase hex) exists in lookup then that is used
  • Otherwise replaceFn(charCode) is called and the result used if replaceFn is a function
  • If replaceFn is a string, that is used
  • Or finally if nothing else matches, the character is ignored

For instance:


let unicodeRemap = {
  0x20ac:"\u0080", // Euro symbol
  0x2026:"\u0085", // Ellipsis
};
E.decodeUTF8("UTF-8 Euro: \u00e2\u0082\u00ac", unicodeRemap, '[?]') == "UTF-8 Euro: \u0080"

Note: This is not available in devices with low flash memory

E.defrag

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Call type:

E.defrag()

Description

BETA: defragment memory!

Note: This is not available in devices with low flash memory

E.dumpFragmentation

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Call type:

E.dumpFragmentation()

Description

Show fragmentation.

  • is free space
  • # is a normal variable
  • L is a locked variable (address used, cannot be moved)
  • = represents data in a Flat String (must be contiguous)

Note: This is not available in devices with low flash memory

E.dumpFreeList

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Call type:

E.dumpFreeList()

Description

Dump any locked variables that aren't referenced from global - for debugging memory leaks only.

Note: This is not available in release builds

E.dumpLockedVars

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Call type:

E.dumpLockedVars()

Description

Dump any locked variables that aren't referenced from global - for debugging memory leaks only.

Note: This does a linear scan over memory, finding variables that are currently locked. In some cases it may show variables like Unknown 66 which happen when part of a string has ended up placed in memory ahead of the String that it's part of. See https://github.com/espruino/Espruino/issues/2345

Note: This is not available in release builds

E.dumpStr

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Call type:

E.dumpStr()

Returns

A String

Description

Get the current interpreter state in a text form such that it can be copied to a new device

Note: This is not available in devices with low flash memory

E.dumpTimers

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Call type:

E.dumpTimers()

Description

Output the current list of Utility Timer Tasks - for debugging only

Note: This is not available in devices with low flash memory

E.dumpVariables

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Call type:

E.dumpVariables()

Description

Dumps a comma-separated list of all allocated variables along with the variables they link to. Can be used to visualise where memory is used.

Note: This is not available in devices with low flash memory

E.enableWatchdog

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Call type:

E.enableWatchdog(timeout, isAuto)

Parameters

timeout - The timeout in seconds before a watchdog reset

isAuto - If undefined or true, the watchdog is kicked automatically. If not, you must call E.kickWatchdog() yourself

Description

Enable the watchdog timer. This will reset Espruino if it isn't able to return to the idle loop within the timeout.

If isAuto is false, you must call E.kickWatchdog() yourself every so often or the chip will reset.


E.enableWatchdog(0.5); // automatic mode
while(1); // Espruino will reboot because it has not been idle for 0.5 sec


E.enableWatchdog(1, false);
setInterval(function() {
  if (everything_ok)
    E.kickWatchdog();
}, 500);
// Espruino will now reset if everything_ok is false,
// or if the interval fails to be called

NOTE: This is only implemented on STM32, nRF5x and ESP32 devices (all official Espruino boards).

NOTE:* On STM32 (Pico, WiFi, Original) with setDeepSleep(1) you need to explicitly wake Espruino up with an interval of less than the watchdog timeout or the watchdog will fire and the board will reboot. You can do this with setInterval("", time_in_milliseconds). *NOTE: On ESP32, the timeout will be rounded to the nearest second.

Note: This is not available in devices with low flash memory

event E.errorFlag

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Call type:

E.on('errorFlag', function(errorFlags) { ... });

Parameters

errorFlags - An array of new error flags, as would be returned by E.getErrorFlags(). Error flags that were present before won't be reported.

Description

This event is called when an error is created by Espruino itself (rather than JS code) which changes the state of the error flags reported by E.getErrorFlags()

This could be low memory, full buffers, UART overflow, etc. E.getErrorFlags() has a full description of each type of error.

This event will only be emitted when error flag is set. If the error flag was already set nothing will be emitted. To clear error flags so that you do get a callback each time a flag is set, call E.getErrorFlags().

E.FFT

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Call type:

E.FFT(arrReal, arrImage, inverse)

Parameters

arrReal - An array of real values

arrImage - An array of imaginary values (or if undefined, all values will be taken to be 0)

inverse - Set this to true if you want an inverse FFT - otherwise leave as 0

Description

Performs a Fast Fourier Transform (FFT) in 32 bit floats on the supplied data and writes it back into the original arrays. Note that if only one array is supplied, the data written back is the modulus of the complex result sqrt(r*r+i*i).

In order to perform the FFT, there has to be enough room on the stack to allocate two arrays of 32 bit floating point numbers - this will limit the maximum size of FFT possible to around 1024 items on most platforms.

Note: on the Original Espruino board, FFTs are performed in 64bit arithmetic as there isn't space to include the 32 bit maths routines (2x more RAM is required).

Note: This is not available in devices with low flash memory

E.fromUTF8

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Call type:

E.fromUTF8(str)

Parameters

str - The string to check

Returns

A String

Description

Given a UTF8 String (see E.asUTF8) this returns the underlying representation of that String.


E.fromUTF8("\u03C0") == "\xCF\x80"

NOTE: UTF8 is currently only available on Bangle.js devices

Note: This is not available in devices with low flash memory

E.getAddressOf

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Call type:

E.getAddressOf(v, flatAddress)

Parameters

v - A variable to get the address of

flatAddress - (boolean) If true and a Flat String or Flat ArrayBuffer is supplied, return the address of the data inside it - otherwise 0. If false (the default) return the address of the JsVar itself.

Returns

The address of the given variable

Description

Return the address in memory of the given variable. This can then be used with peek and poke functions. However, changing data in JS variables directly (flatAddress=false) will most likely result in a crash.

This functions exists to allow embedded targets to set up peripherals such as DMA so that they write directly to JS variables.

See http://www.espruino.com/Internals for more information

Note: This is not available in devices with low flash memory

E.getAnalogVRef

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Call type:

E.getAnalogVRef()

Returns

The voltage (in Volts) that a reading of 1 from analogRead actually represents - usually around 3.3v

Description

Check the internal voltage reference. To work out an actual voltage of an input pin, you can use analogRead(pin)*E.getAnalogVRef()

Note: This value is calculated by reading the voltage on an internal voltage reference with the ADC. It will be slightly noisy, so if you need this for accurate measurements we'd recommend that you call this function several times and average the results.

While this is implemented on Espruino boards, it may not be implemented on other devices. If so it'll return NaN.

Note: This is not available in devices with low flash memory

E.getConsole

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Call type:

E.getConsole()

Returns

The current console device as a string, or just null if the console is null

Description

Returns the current console device - see E.setConsole for more information.

E.getErrorFlags

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Call type:

E.getErrorFlags()

Returns

An array of error flags

Description

Get and reset the error flags. Returns an array that can contain:

'FIFO_FULL': The receive FIFO filled up and data was lost. This could be state transitions for setWatch, or received characters.

'BUFFER_FULL': A buffer for a stream filled up and characters were lost. This can happen to any stream - Serial,HTTP,etc.

'CALLBACK': A callback (setWatch, setInterval, on('data',...)) caused an error and so was removed.

'LOW_MEMORY': Memory is running low - Espruino had to run a garbage collection pass or remove some of the command history

'MEMORY': Espruino ran out of memory and was unable to allocate some data that it needed.

'UART_OVERFLOW' : A UART received data but it was not read in time and was lost

Note: This is not available in devices with low flash memory

E.getFlags

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Call type:

E.getFlags()

Returns

An object containing flag names and their values

Description

Get Espruino's interpreter flags that control the way it handles your JavaScript code.

  • deepSleep - Allow deep sleep modes (also set by setDeepSleep)
  • pretokenise - When adding functions, pre-minify them and tokenise reserved words
  • unsafeFlash - Some platforms stop writes/erases to interpreter memory to stop you bricking the device accidentally - this removes that protection
  • unsyncFiles - When writing files, don't flush all data to the SD card after each command (the default is to flush). This is much faster, but can cause filesystem damage if power is lost without the filesystem unmounted.

E.getPowerUsage

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Call type:

E.getPowerUsage()

Returns

An object detailing power usage in microamps

Description

This function returns an object detailing the current estimated power usage of the Espruino device in microamps (uA). It is not intended to be a replacement for measuring actual power consumption, but can be useful for finding obvious power draws.

Where an Espruino device has outputs that are connected to other things, those are not included in the power usage figures.

Results look like:


{
  device: {
    CPU : 2000, // microcontroller
    LCD : 100, // LCD
    // ...
  },
  total : 5500 // estimated usage in microamps
}

Note: Currently only nRF52-based devices have variable CPU power usage figures. These are based on the time passed for each SysTick event, so under heavy usage the figure will update within 0.3s, but under low CPU usage it could take minutes for the CPU usage figure to update.

Note: On Jolt.js we take account of internal resistance on H0/H2/H4/H6 where we can measure voltage. H1/H3/H5/H7 cannot be measured.

E.getRTCPrescaler

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Call type:

E.getRTCPrescaler(calibrate)

Parameters

calibrate - If false, the current value. If true, the calculated 'correct' value

Returns

The RTC prescaler's current value

Description

Gets the RTC's current prescaler value if calibrate is undefined or false.

If calibrate is true, the low speed oscillator's speed is calibrated against the high speed oscillator (usually +/- 20 ppm) and a suggested value to be fed into E.setRTCPrescaler(...) is returned.

See E.setRTCPrescaler for more information.

Note: This is only available in Espruino Pico boards and Espruino WiFi boards and 'Original' Espruino boards

E.getSizeOf

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Call type:

E.getSizeOf(v, depth)

Parameters

v - A variable to get the size of

depth - The depth that detail should be provided for. If depth<=0 or undefined, a single integer will be returned

Returns

Information about the variable size - see below

Description

Return the number of variable blocks used by the supplied variable. This is useful if you're running out of memory and you want to be able to see what is taking up most of the available space.

If depth>0 and the variable can be recursed into, an array listing all property names (including internal Espruino names) and their sizes is returned. If depth>1 there is also a more field that inspects the objects' children's children.

For instance E.getSizeOf(function(a,b) { }) returns 5.

But E.getSizeOf(function(a,b) { }, 1) returns:


 [
  {
    "name": "a",
    "size": 1 },
  {
    "name": "b",
    "size": 1 },
  {
    "name": "\xFFcod",
    "size": 2 }
 ]

In this case setting depth to 2 will make no difference as there are no more children to traverse.

See http://www.espruino.com/Internals for more information

Note: This is not available in devices with low flash memory

E.getTemperature

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Call type:

E.getTemperature()

Returns

The temperature in degrees C

Description

Use the microcontroller's internal thermistor to work out the temperature.

On Puck.js v2.0 this will use the on-board PCT2075TP temperature sensor, but on other devices it may not be desperately well calibrated.

While this is implemented on Espruino boards, it may not be implemented on other devices. If so it'll return NaN.

Note:* This is not entirely accurate and varies by a few degrees from chip to chip. It measures the *die temperature, so when connected to USB it could be reading 10 over degrees C above ambient temperature. When running from battery with setDeepSleep(true) it is much more accurate though.

E.HSBtoRGB

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Call type:

E.HSBtoRGB(hue, sat, bri, format)

Parameters

hue - The hue, as a value between 0 and 1

sat - The saturation, as a value between 0 and 1

bri - The brightness, as a value between 0 and 1

format - If true or 1, return an array of [R,G,B] values betwen 0 and 255. If 16, return a 16 bit number. undefined/24 is the same as normal (returning a 24 bit number)

Returns

A 24 bit number containing bytes representing red, green, and blue 0xBBGGRR. Or if asArray is true, an array [R,G,B]

Description

Convert hue, saturation and brightness to red, green and blue (packed into an integer if asArray==false or an array if asArray==true).

This replaces Graphics.setColorHSB and Graphics.setBgColorHSB. On devices with 24 bit colour it can be used as: Graphics.setColor(E.HSBtoRGB(h, s, b)), or on devices with 26 bit colour use Graphics.setColor(E.HSBtoRGB(h, s, b, 16))

You can quickly set RGB items in an Array or Typed Array using array.set(E.HSBtoRGB(h, s, b, true), offset), which can be useful with arrays used with require("neopixel").write.

Note: This is not available in devices with low flash memory

E.hwRand

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Call type:

E.hwRand()

Returns

A random number

Description

Unlike 'Math.random()' which uses a pseudo-random number generator, this method reads from the internal voltage reference several times, XOR-ing and rotating to try and make a relatively random value from the noise in the signal.

Note: This is not available in devices with low flash memory

event E.init

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Call type:

E.on('init', function() { ... });

Description

This event is called right after the board starts up, and has a similar effect to creating a function called onInit.

For example to write "Hello World" every time Espruino starts, use:


E.on('init', function() {
  console.log("Hello World!");
});

Note:* that subsequent calls to E.on('init', will *add a new handler, rather than replacing the last one. This allows you to write modular code - something that was not possible with onInit.

E.isUTF8

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Call type:

E.isUTF8(str)

Parameters

str - The string to check

Returns

True if the given String is treated as UTF8 by Espruino

Description

By default, strings in Espruino are standard 8 bit binary strings unless they contain Unicode chars or a \u#### escape code that doesn't map to the range 0..255.

This checks if a String is being treated by Espruino as a UTF8 String

See E.asUTF8 to convert to a UTF8 String

NOTE: UTF8 is currently only available on Bangle.js devices

Note: This is not available in devices with low flash memory

E.kickWatchdog

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Call type:

E.kickWatchdog()

Description

Kicks a Watchdog timer set up with E.enableWatchdog(..., false). See E.enableWatchdog for more information.

NOTE: This is only implemented on STM32 and nRF5x devices (all official Espruino boards).

Note: This is not available in devices with low flash memory

event E.kill

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Call type:

E.on('kill', function() { ... });

Description

This event is called just before the device shuts down for commands such as reset(), load(), save(), E.reboot() or Bangle.off()

For example to write "Bye!" just before shutting down use:


E.on('kill', function() {
  console.log("Bye!");
});

NOTE: This event is not called when the device is 'hard reset' - for example by removing power, hitting an actual reset button, or via a Watchdog timer reset.

E.lockConsole

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Call type:

E.lockConsole()

Description

If a password has been set with E.setPassword(), this will lock the console so the password needs to be entered to unlock it.

E.lookupNoCase

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Call type:

E.lookupNoCase(haystack, needle, returnKey)

Parameters

haystack - The Array/Object/Function to search

needle - The key to search for

returnKey - If true, return the key, else return the value itself

Returns

The value in the Object matching 'needle', or if returnKey==true the key's name - or undefined

Description

Search in an Object, Array, or Function

E.mapInPlace

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Call type:

E.mapInPlace(from, to, map, bits)

Parameters

from - An ArrayBuffer to read elements from

to - An ArrayBuffer to write elements too

map - An array or function(value,index) to use to map one element to another, or undefined to provide no mapping

bits - If specified, the number of bits per element (MSB first) - otherwise use a 1:1 mapping. If negative, use LSB first.

Description

Take each element of the from array, look it up in map (or call map(value,index) if it is a function), and write it into the corresponding element in the to array.

You can use an array to map:


var a = new Uint8Array([1,2,3,1,2,3]);
var lut = new Uint8Array([128,129,130,131]);
E.mapInPlace(a, a, lut);
// a = [129, 130, 131, 129, 130, 131]

Or undefined to pass straight through, or a function to do a normal 'mapping':


var a = new Uint8Array([0x12,0x34,0x56,0x78]);
var b = new Uint8Array(8);
E.mapInPlace(a, b, undefined); // straight through
// b = [0x12,0x34,0x56,0x78,0,0,0,0]
E.mapInPlace(a, b, (value,index)=>index); // write the index in the first 4 (because a.length==4)
// b = [0,1,2,3,4,0,0,0]
E.mapInPlace(a, b, undefined, 4); // 4 bits from 8 bit input -> 2x as many outputs, msb-first
// b = [1, 2, 3, 4, 5, 6, 7, 8]
 E.mapInPlace(a, b, undefined, -4); // 4 bits from 8 bit input -> 2x as many outputs, lsb-first
// b = [2, 1, 4, 3, 6, 5, 8, 7]
E.mapInPlace(a, b, a=>a+2, 4);
// b = [3, 4, 5, 6, 7, 8, 9, 10]
var b = new Uint16Array(4);
E.mapInPlace(a, b, undefined, 12); // 12 bits from 8 bit input, msb-first
// b = [0x123, 0x456, 0x780, 0]
E.mapInPlace(a, b, undefined, -12); // 12 bits from 8 bit input, lsb-first
// b = [0x412, 0x563, 0x078, 0]

Note: This is not available in devices with low flash memory

E.memoryArea

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Call type:

E.memoryArea(addr, len)

Parameters

addr - The address of the memory area

len - The length (in bytes) of the memory area

Returns

A String

Description

This creates and returns a special type of string, which references a specific address in memory. It can be used in order to use sections of Flash memory directly in Espruino (for example Storage uses it to allow files to be read directly from Flash).

Note: As of 2v21, Calling E.memoryArea with an address of 0 will return undefined

E.memoryMap

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Call type:

E.memoryMap(baseAddress, registers)

Parameters

baseAddress - The base address (added to every address in registers)

registers - An object containing {name:address}

Returns

An object where each field is memory-mapped to a register.

Description

Create an object where every field accesses a specific 32 bit address in the microcontroller's memory. This is perfect for accessing on-chip peripherals.


// for NRF52 based chips
var GPIO = E.memoryMap(0x50000000,{OUT:0x504, OUTSET:0x508, OUTCLR:0x50C, IN:0x510, DIR:0x514, DIRSET:0x518, DIRCLR:0x51C});
GPIO.DIRSET = 1; // set GPIO0 to output
GPIO.OUT ^= 1; // toggle the output state of GPIO0

Note: This is not available in devices with low flash memory

E.nativeCall

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Call type:

E.nativeCall(addr, sig, data)

Parameters

addr - The address in memory of the function (or offset in data if it was supplied

sig - The signature of the call, returnType (arg1,arg2,...). Allowed types are void,bool,int,double,float,Pin,JsVar

data - (Optional) A string containing the function itself. If not supplied then 'addr' is used as an absolute address.

Returns

The native function

Description

ADVANCED: It's very easy to crash Espruino using this function if you get the code/arguments you supply wrong!

Create a native function that executes the code at the given address, e.g. E.nativeCall(0x08012345,'double (double,double)')(1.1, 2.2)

If you're executing a thumb function, you'll almost certainly need to set the bottom bit of the address to 1.

Note it's not guaranteed that the call signature you provide can be used - there are limits on the number of arguments allowed (5).

When supplying data, if it is a 'flat string' then it will be used directly, otherwise it'll be converted to a flat string and used.

The argument types in sig are:

  • void - returns nothing
  • bool - boolean value
  • int - 32 bit integer
  • double - 64 bit floating point
  • float - 32 bit floating point (2v21 and later)
  • Pin - Espruino 'pin' value (8 bit integer)
  • JsVar - Pointer to an Espruino JsVar structure

Note: This is not available in devices with low flash memory

E.openFile

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Call type:

E.openFile(path, mode)

Parameters

path - the path to the file to open.

mode - The mode to use when opening the file. Valid values for mode are 'r' for read, 'w' for write new, 'w+' for write existing, and 'a' for append. If not specified, the default is 'r'.

Returns

A File object

Description

Open a file

E.pipe

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Call type:

E.pipe(source, destination, options)

Parameters

source - The source file/stream that will send content. As of 2v19 this can also be a String

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=64, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe one stream to another.

This can be given any object with a read method as a source, and any object with a .write(data) method as a destination.

Data will be piped from source to destination in the idle loop until source.read(...) returns undefined.

For instance:

``` // Print a really big string to the console, 1 character at a time and write 'Finished!' at the end E.pipe("This is a really big String", {write: print}, {chunkSize:1, complete:()=>print("Finished!")});

// Pipe the numbers 1 to 100 to a StorageFile in Storage E.pipe({ n:0, read : function() { if (this.n<100) return (this.n++)+"\n"; }}, require("Storage").open("testfile","w"));

// Pipe a StorageFile straight to the Bluetooth UART E.pipe(require("Storage").open("testfile","r"), Bluetooth);

// Pipe a normal file in Storage (not StorageFile) straight to the Bluetooth UART E.pipe(require("Storage").read("blob.txt"), Bluetooth);

// Pipe a normal file in Storage as a response to an HTTP request function onPageRequest(req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); E.pipe(require("Storage").read("webpage.txt"), res); } require("http").createServer(onPageRequest).listen(80); ```

Note: This is not available in devices with low flash memory

E.reboot

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Call type:

E.reboot()

Description

Forces a hard reboot of the microcontroller - as close as possible to if the reset pin had been toggled.

Note: This is different to reset(), which performs a software reset of Espruino (resetting the interpreter and pin states, but not all the hardware)

E.reverseByte

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Call type:

E.reverseByte(x)

Parameters

x - A byte value to reverse the bits of

Returns

The byte with reversed bits

Description

Reverse the 8 bits in a byte, swapping MSB and LSB.

For example, E.reverseByte(0b10010000) == 0b00001001.

Note that you can reverse all the bytes in an array with:

arr =
arr.map(E.reverseByte)

Note: This is not available in devices with low flash memory

E.sendUSBHID

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Call type:

E.sendUSBHID(data)

Parameters

data - An array of bytes to send as a USB HID packet

Returns

1 on success, 0 on failure

E.setBootCode

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Call type:

E.setBootCode(code, alwaysExec)

Parameters

code - The code to execute (as a string)

alwaysExec - Whether to always execute the code (even after a reset)

Description

This writes JavaScript code into Espruino's flash memory, to be executed on startup. It differs from save() in that save() saves the whole state of the interpreter, whereas this just saves JS code that is executed at boot.

Code will be executed before onInit() and E.on('init', ...).

If alwaysExec is true, the code will be executed even after a call to reset(). This is useful if you're making something that you want to program, but you want some code that is always built in (for instance setting up a display or keyboard).

To remove boot code that has been saved previously, use E.setBootCode("")

Note: this removes any code that was previously saved with save()

E.setClock

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Call type:

E.setClock(options)

Parameters

options - Platform-specific options for setting clock speed

Returns

The actual frequency the clock has been set to

Description

This sets the clock frequency of Espruino's processor. It will return 0 if it is unimplemented or the clock speed cannot be changed.

Note: On pretty much all boards, UART, SPI, I2C, PWM, etc will change frequency and will need setting up again in order to work.

STM32F4

Options is of the form { M: int, N: int, P: int, Q: int } - see the 'Clocks' section of the microcontroller's reference manual for what these mean.

  • System clock = 8Mhz * N / ( M * P )
  • USB clock (should be 48Mhz) = 8Mhz * N / ( M * Q )

Optional arguments are:

  • latency - flash latency from 0..15
  • PCLK1 - Peripheral clock 1 divisor (default: 2)
  • PCLK2 - Peripheral clock 2 divisor (default: 4)

The Pico's default is {M:8, N:336, P:4, Q:7, PCLK1:2, PCLK2:4}, use

{M:8,
N:336, P:8, Q:7, PCLK:1, PCLK2:2}
to halve the system clock speed while keeping the peripherals running at the same speed (omitting PCLK1/2 will lead to the peripherals changing speed too).

On STM32F4 boards (e.g. Espruino Pico), the USB clock needs to be kept at 48Mhz or USB will fail to work. You'll also experience USB instability if the processor clock falls much below 48Mhz.

ESP8266

Just specify an integer value, either 80 or 160 (for 80 or 160Mhz)

Note: This is not available in devices with low flash memory

E.setConsole

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Call type:

E.setConsole(device, options)

Parameters

device -

options - [optional] object of options, see below

Description

Changes the device that the JS console (otherwise known as the REPL) is attached to. If the console is on a device, that device can be used for programming Espruino.

Rather than calling Serial.setConsole you can call E.setConsole("DeviceName").

This is particularly useful if you just want to remove the console. E.setConsole(null) will make the console completely inaccessible.

device may be "Serial1","USB","Bluetooth","Telnet","Terminal", any other hardware Serial device, or null to disable the console completely.

options is of the form:


{
  force : bool // default false, force the console onto this device so it does not move
               //   if false, changes in connection state (e.g. USB/Bluetooth) can move
               //   the console automatically.
}

Note: This is not available in devices with low flash memory

E.setDST

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Call type:

E.setDST(params, ...)

Parameters

params, ... - An array containing the settings for DST, or undefined to disable

Description

Set the daylight savings time parameters to be used with Date objects.

The parameters are - dstOffset: The number of minutes daylight savings time adds to the clock (usually 60) - set to 0 to disable DST - timezone: The time zone, in minutes, when DST is not in effect - positive east of Greenwich - startDowNumber: The index of the day-of-week in the month when DST starts - 0 for first, 1 for second, 2 for third, 3 for fourth and 4 for last - startDow: The day-of-week for the DST start calculation - 0 for Sunday, 6 for Saturday - startMonth: The number of the month that DST starts - 0 for January, 11 for December - startDayOffset: The number of days between the selected day-of-week and the actual day that DST starts - usually 0 - startTimeOfDay: The number of minutes elapsed in the day before DST starts - endDowNumber: The index of the day-of-week in the month when DST ends - 0 for first, 1 for second, 2 for third, 3 for fourth and 4 for last - endDow: The day-of-week for the DST end calculation - 0 for Sunday, 6 for Saturday - endMonth: The number of the month that DST ends - 0 for January, 11 for December - endDayOffset: The number of days between the selected day-of-week and the actual day that DST ends - usually 0 - endTimeOfDay: The number of minutes elapsed in the day before DST ends

To determine what the dowNumber, dow, month, dayOffset, timeOfDay parameters should be, start with a sentence of the form "DST starts on the last Sunday of March (plus 0 days) at 03:00". Since it's the last Sunday, we have startDowNumber = 4, and since it's Sunday, we have startDow = 0. That it is March gives us startMonth = 2, and that the offset is zero days, we have startDayOffset = 0. The time that DST starts gives us startTimeOfDay = 3*60.

"DST ends on the Friday before the second Sunday in November at 02:00" would give us endDowNumber=1, endDow=0, endMonth=10, endDayOffset=-2 and endTimeOfDay=120.

Using Ukraine as an example, we have a time which is 2 hours ahead of GMT in winter (EET) and 3 hours in summer (EEST). DST starts at 03:00 EET on the last Sunday in March, and ends at 04:00 EEST on the last Sunday in October. So someone in Ukraine might call E.setDST(60,120,4,0,2,0,180,4,0,9,0,240);

Examples:


// United Kingdom
E.setDST(60,0,4,0,2,0,60,4,0,9,0,120);
// California, USA
E.setDST(60,-480,1,0,2,0,120,0,0,10,0,120);
// Or adjust -480 (-8 hours) for other US states
// Ukraine
E.setDST(60,120,4,0,2,0,180,4,0,9,0,240);

Note: This is not compatible with E.setTimeZone(). Calling E.setTimeZone() after this will disable DST.

Note: This is not available in ESPRNODAYLIGHT_SAVING

E.setFlags

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Call type:

E.setFlags(flags)

Parameters

flags - An object containing flag names and boolean values. You need only specify the flags that you want to change.

Description

Set the Espruino interpreter flags that control the way it handles your JavaScript code.

Run E.getFlags() and check its description for a list of available flags and their values.

E.setPassword

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Call type:

E.setPassword(password)

Parameters

password - The password - max 20 chars

Description

Set a password on the console (REPL). When powered on, Espruino will then demand a password before the console can be used. If you want to lock the console immediately after this you can call E.lockConsole()

To remove the password, call this function with no arguments.

Note: There is no protection against multiple password attempts, so someone could conceivably try every password in a dictionary.

Note: This password is stored in memory in plain text. If someone is able to execute arbitrary JavaScript code on the device (e.g., you use eval on input from unknown sources) or read the device's firmware then they may be able to obtain it.

E.setRTCPrescaler

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Call type:

E.setRTCPrescaler(prescaler)

Parameters

prescaler - The amount of counts for one second of the RTC - this is a 15 bit integer value (0..32767)

Description

Sets the RTC's prescaler's maximum value. This is the counter that counts up on each oscillation of the low speed oscillator. When the prescaler counts to the value supplied, one second is deemed to have passed.

By default this is set to the oscillator's average speed as specified in the datasheet, and usually that is fine. However on early Espruino Pico boards the STM32F4's internal oscillator could vary by as much as 15% from the value in the datasheet. In that case you may want to alter this value to reflect the true RTC speed for more accurate timekeeping.

To change the RTC's prescaler value to a computed value based on comparing against the high speed oscillator, just run the following command, making sure it's done a few seconds after the board starts up:


E.setRTCPrescaler(E.getRTCPrescaler(true));

When changing the RTC prescaler, the RTC 'follower' counters are reset and it can take a second or two before readings from getTime are stable again.

To test, you can connect an input pin to a known frequency square wave and then use setWatch. If you don't have a frequency source handy, you can check against the high speed oscillator:


// connect pin B3 to B4
analogWrite(B3, 0.5, {freq:0.5});
setWatch(function(e) {
  print(e.time - e.lastTime);
}, B4, {repeat:true});

Note: This is only used on official Espruino boards containing an STM32 microcontroller. Other boards (even those using an STM32) don't use the RTC and so this has no effect.

Note: This is only available in Espruino Pico boards and Espruino WiFi boards and 'Original' Espruino boards

E.setTimeZone

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Call type:

E.setTimeZone(zone)

Parameters

zone - The time zone in hours

Description

Set the time zone to be used with Date objects.

For example E.setTimeZone(1) will be GMT+0100

Time can be set with setTime.

Note: If daylight savings time rules have been set with E.setDST(), calling E.setTimeZone() will remove them and move back to using a static timezone that doesn't change based on the time of year.

E.setUSBHID

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Call type:

E.setUSBHID(opts)

Parameters

opts - An object containing at least reportDescriptor, an array representing the report descriptor. Pass undefined to disable HID.

Description

USB HID will only take effect next time you unplug and re-plug your Espruino. If you're disconnecting it from power you'll have to make sure you have save()d after calling this function.

Note: This is only available in devices that support USB HID (Espruino Pico and Espruino WiFi)

E.srand

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Call type:

E.srand(v)

Parameters

v - The 32 bit integer seed to use for the random number generator

Description

Set the seed for the random number generator used by Math.random().

Note: This is not available in devices with low flash memory

E.stopEventPropagation

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Call type:

E.stopEventPropagation()

Description

When using events with X.on('foo', function() { ... }) and then X.emit('foo') you might want to stop subsequent event handlers from being executed.

Calling this function doing the execution of events will ensure that no subsequent event handlers are executed.


var X = {}; // in Espruino all objects are EventEmitters
X.on('foo', function() { print("A"); })
X.on('foo', function() { print("B"); E.stopEventPropagation(); })
X.on('foo', function() { print("C"); })
X.emit('foo');
// prints A,B but not C

E.sum

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Call type:

E.sum(arr)

Parameters

arr - The array to sum

Returns

The sum of the given buffer

Description

Sum the contents of the given Array, String or ArrayBuffer and return the result

Note: This is not available in devices with low flash memory

E.toArrayBuffer

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Call type:

E.toArrayBuffer(str)

Parameters

str - The string to convert to an ArrayBuffer

Returns

An ArrayBuffer that uses the given string

Description

Create an ArrayBuffer from the given string. This is done via a reference, not a copy - so it is very fast and memory efficient.

Note that this is an ArrayBuffer, not a Uint8Array. To get one of those, do: new Uint8Array(E.toArrayBuffer('....')).

E.toFlatString

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Call type:

E.toFlatString(args, ...)

Parameters

args, ... - The arguments to convert to a Flat String

Returns

A Flat String (or undefined)

Description

Returns a Flat String representing the data in the arguments, or undefined if one can't be allocated.

This provides the same behaviour that E.toString had in Espruino before 2v18 - see E.toString for more information.

E.toJS

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Call type:

E.toJS(arg)

Parameters

arg - The JS variable to convert to a string

Returns

A String

Description

This performs the same basic function as JSON.stringify, however JSON.stringify adds extra characters to conform to the JSON spec which aren't required if outputting JS.

E.toJS will also stringify JS functions, whereas JSON.stringify ignores them.

For example:

  • JSON.stringify({a:1,b:2}) == '{"a":1,"b":2}'
  • E.toJS({a:1,b:2}) == '{a:1,b:2}'

Note: Strings generated with E.toJS can't be reliably parsed by JSON.parse - however they are valid JS so will work with eval (but this has security implications if you don't trust the source of the string).

On the desktop JSON5 parsers will parse the strings produced by E.toJS without trouble.

E.toString

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Call type:

E.toString(args, ...)

Parameters

args, ... - The arguments to convert to a String

Returns

A String

Description

Returns a String representing the data in the arguments.

This creates a string from the given arguments in the same way as E.toUint8Array. If each argument is:

  • A String or an Array, each element is traversed and added as an 8 bit character
  • {data : ..., count : N} causes data to be repeated count times
  • {callback : fn} calls the function and adds the result
  • Anything else is converted to a character directly.

In the case where there's one argument which is an 8 bit typed array backed by a flat string of the same length, the backing string will be returned without doing a copy or other allocation. The same applies if there's a single argument which is itself a flat string.

```JS E.toString(0,1,2,"Hi",3) "\0\1\2Hi\3" E.toString(1,2,{data:[3,4], count:4},5,6) "\1\2\3\4\3\4\3\4\3\4\5\6"

E.toString(1,2,{callback : () => "Hello World"},5,6) ="\1\2Hello World\5\6" ```

Note: Prior to Espruino 2v18 E.toString would always return a flat string, or would return undefined if one couldn't be allocated. Now, it will return a normal (fragmented) String if a contiguous chunk of memory cannot be allocated. You can still check if the returned value is a Flat string using E.getAddressOf(str, true)!=0, or can use E.toFlatString instead.

event E.touch

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Call type:

E.on('touch', function(x, y, b) { ... });

Parameters

x - X coordinate in display coordinates

y - Y coordinate in display coordinates

b - Touch count - 0 for released, 1 for pressed

Description

This event is called when a full touchscreen device on an Espruino is interacted with.

Note: This event is not implemented on Bangle.js because it only has a two area touchscreen.

To use the touchscreen to draw lines, you could do:


var last;
E.on('touch',t=>{
  if (last) g.lineTo(t.x, t.y);
  else g.moveTo(t.x, t.y);
  last = t.b;
});

E.toUint8Array

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Call type:

E.toUint8Array(args, ...)

Parameters

args, ... - The arguments to convert to a Uint8Array

Returns

A Uint8Array

Description

This creates a Uint8Array from the given arguments. These are handled as follows:

  • Number -> read as an integer, using the lowest 8 bits
  • String -> use each character's numeric value (e.g. String.charCodeAt(...))
  • Array -> Call itself on each element
  • ArrayBuffer or Typed Array -> use the lowest 8 bits of each element
  • Object:
    • {data:..., count: int} -> call itself object.count times, on object.data
    • {callback : function} -> call the given function, call itself on return value

For example:


E.toUint8Array([1,2,3])
=new Uint8Array([1, 2, 3])
E.toUint8Array([1,{data:2,count:3},3])
=new Uint8Array([1, 2, 2, 2, 3])
E.toUint8Array("Hello")
=new Uint8Array([72, 101, 108, 108, 111])
E.toUint8Array(["hi",{callback:function() { return [1,2,3] }}])
=new Uint8Array([104, 105, 1, 2, 3])

E.unmountSD

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Call type:

E.unmountSD()

Description

Unmount the SD card, so it can be removed. If you remove the SD card without calling this you may cause corruption, and you will be unable to access another SD card until you reset Espruino or call E.unmountSD().

E.variance

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Call type:

E.variance(arr, mean)

Parameters

arr - The array to work out the variance for

mean - The mean value of the array

Returns

The variance of the given buffer

Description

Work out the variance of the contents of the given Array, String or ArrayBuffer and return the result. This is equivalent to

v=0;for (i in arr)
v+=Math.pow(mean-arr[i],2)

Note: This is not available in devices with low flash memory

Error Class

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The base class for runtime errors

Methods and Fields

constructor Error

View MDN documentation

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Call type:

new Error(message)

Parameters

message - [optional] An message string

Returns

An Error object

Description

Creates an Error object

function Error.toString

View MDN documentation

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Call type:

function Error.toString()

Returns

A String

Ethernet Class

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An instantiation of an Ethernet network adaptor

Methods and Fields

function Ethernet.getHostname

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Call type:

function Ethernet.getHostname(callback)

Parameters

callback - [optional] An callback(err,hostname) function to be called back with the status information.

Returns

See description above

Description

Returns the hostname

Note: This is only available in builds with support for WIZnet Ethernet modules built in

function Ethernet.getIP

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Call type:

function Ethernet.getIP(options)

Parameters

options - [optional] An callback(err, ipinfo) function to be called back with the IP information.

Returns

See description above

Description

Get the current IP address, subnet, gateway and mac address.

Note: This is only available in builds with support for WIZnet Ethernet modules built in

function Ethernet.getStatus

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Call type:

function Ethernet.getStatus(options)

Parameters

options - [optional] An callback(err, status) function to be called back with the status information.

Returns

See description above

Description

Get the current status of the ethernet device

Note: This is only available in builds with support for WIZnet Ethernet modules built in

function Ethernet.setHostname

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Call type:

function Ethernet.setHostname(hostname, callback)

Parameters

hostname - hostname as string

callback - [optional] An callback(err) function to be called back with null or error text.

Returns

True on success

Description

Set hostname used during the DHCP request. Minimum 8 and maximum 12 characters, best set before calling eth.setIP(). Default is WIZnet010203, 010203 is the default nic as part of the mac.

Note: This is only available in builds with support for WIZnet Ethernet modules built in

function Ethernet.setIP

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Call type:

function Ethernet.setIP(options, callback)

Parameters

options - Object containing IP address options { ip : '1.2.3.4', subnet : '...', gateway: '...', dns:'...', mac:':::::' }, or do not supply an object in order to force DHCP.

callback - [optional] An callback(err) function to invoke when ip is set. err==null on success, or a string on failure.

Returns

True on success

Description

Set the current IP address or get an IP from DHCP (if no options object is specified)

If 'mac' is specified as an option, it must be a string of the form "00:01:02:03:04:05" The default mac is 00:08:DC:01:02:03.

Note: This is only available in builds with support for WIZnet Ethernet modules built in

File Class

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This is the File object - it allows you to stream data to and from files (As opposed to the require('fs').readFile(..) style functions that read an entire file).

To create a File object, you must type

var fd =
E.openFile('filepath','mode')
- see E.openFile for more information.

Note: If you want to remove an SD card after you have started using it, you must call E.unmountSD() or you may cause damage to the card.

Methods and Fields

function File.close

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Call type:

function File.close()

Description

Close an open file.

function File.pipe

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Call type:

function File.pipe(destination, options)

Parameters

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=32, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this file to a stream (an object with a 'write' method)

Note: This is not available in devices with low flash memory

function File.read

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Call type:

function File.read(length)

Parameters

length - is an integer specifying the number of bytes to read.

Returns

A string containing the characters that were read

Description

Read data in a file in byte size chunks

function File.seek

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Call type:

function File.seek(nBytes)

Parameters

nBytes - is an integer specifying the number of bytes to skip forwards.

Description

Seek to a certain position in the file

function File.skip

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Call type:

function File.skip(nBytes)

Parameters

nBytes - is a positive integer specifying the number of bytes to skip forwards.

Description

Skip the specified number of bytes forward in the file

function File.write

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Call type:

function File.write(buffer)

Parameters

buffer - A string containing the bytes to write

Returns

the number of bytes written

Description

Write data to a file.

Note: By default this function flushes all changes to the SD card, which makes it slow (but also safe!). You can use E.setFlags({unsyncFiles:1}) to disable this behaviour and really speed up writes - but then you must be sure to close all files you are writing before power is lost or you will cause damage to your SD card's filesystem.

Flash Library

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This module allows you to read and write the nonvolatile flash memory of your device.

Also see the Storage library, which provides a safer file-like interface to nonvolatile storage.

It should be used with extreme caution, as it is easy to overwrite parts of Flash memory belonging to Espruino or even its bootloader. If you damage the bootloader then you may need external hardware such as a USB-TTL converter to restore it. For more information on restoring the bootloader see

Advanced
Reflashing
in your board's reference pages.

To see which areas of memory you can and can't overwrite, look at the values reported by process.memory().

Note: On Nordic platforms there are checks in place to help you avoid 'bricking' your device be damaging the bootloader. You can disable these with E.setFlags({unsafeFlash:1})

Methods and Fields

Flash.erasePage

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Call type:

require("Flash").erasePage(addr)

Parameters

addr - An address in the page that is to be erased

Description

Erase a page of flash memory

Note: This is not available in devices with low flash memory

Flash.getFree

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Call type:

require("Flash").getFree()

Returns

Array of objects with addr and length properties

Description

This method returns an array of objects of the form {addr : #, length : #}, representing contiguous areas of flash memory in the chip that are not used for anything.

The memory areas returned are on page boundaries. This means that you can safely erase the page containing any address here, and you won't risk deleting part of the Espruino firmware.

Note: This is not available in devices with low flash memory

Flash.getPage

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Call type:

require("Flash").getPage(addr)

Parameters

addr - An address in memory

Returns

An object of the form { addr : #, length : #}, where addr is the start address of the page, and length is the length of it (in bytes). Returns undefined if no page at address

Description

Returns the start and length of the flash page containing the given address.

Note: This is not available in devices with low flash memory

Flash.read

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Call type:

require("Flash").read(length, addr)

Parameters

length - The amount of data to read (in bytes)

addr - The address to start reading from

Returns

A Uint8Array of data

Description

Read flash memory from the given address

Note: This is not available in devices with low flash memory

Flash.write

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Call type:

require("Flash").write(data, addr)

Parameters

data - The data to write

addr - The address to start writing from

Description

Write data into memory at the given address

In flash memory you may only turn bits that are 1 into bits that are 0. If you're writing data into an area that you have already written (so read doesn't return all 0xFF) you'll need to call erasePage to clear the entire page.

Note: This is not available in devices with low flash memory

Float32Array Class

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This is the built-in JavaScript class for a typed array of 32 bit floating point values.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Float32Array

View MDN documentation

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Call type:

new Float32Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Float64Array Class

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This is the built-in JavaScript class for a typed array of 64 bit floating point values.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Float64Array

View MDN documentation

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Call type:

new Float64Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer). Maximum 65535.

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

fs Library

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This library handles interfacing with a FAT32 filesystem on an SD card. The API is designed to be similar to node.js's - However Espruino does not currently support asynchronous file IO, so the functions behave like node.js's xxxxSync functions. Versions of the functions with 'Sync' after them are also provided for compatibility.

To use this, you must type var fs = require('fs') to get access to the library

See the page on File IO for more information, and for examples on wiring up an SD card if your device doesn't come with one.

Note: If you want to remove an SD card after you have started using it, you must call E.unmountSD() or you may cause damage to the card.

Methods and Fields

fs.appendFile

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Call type:

require("fs").appendFile(path, data)

Parameters

path - The path of the file to write

data - The data to write to the file

Returns

True on success, false on failure

Description

Append the data to the given file, created a new file if it doesn't exist

NOTE: Espruino does not yet support Async file IO, so this function behaves like the 'Sync' version.

fs.appendFileSync

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Call type:

require("fs").appendFileSync(path, data)

Parameters

path - The path of the file to write

data - The data to write to the file

Returns

True on success, false on failure

Description

Append the data to the given file, created a new file if it doesn't exist

Note: This is not available in devices with low flash memory

fs.mkdir

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Call type:

require("fs").mkdir(path)

Parameters

path - The name of the directory to create

Returns

True on success, or false on failure

Description

Create the directory

NOTE: Espruino does not yet support Async file IO, so this function behaves like the 'Sync' version.

Note: This is not available in devices with low flash memory

fs.mkdirSync

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Call type:

require("fs").mkdirSync(path)

Parameters

path - The name of the directory to create

Returns

True on success, or false on failure

Description

Create the directory

Note: This is not available in devices with low flash memory

fs.pipe

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Call type:

require("fs").pipe(source, destination, options)

Parameters

source - The source file/stream that will send content.

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=64, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this file to a destination stream (object which has a .write(data) method).

Note: This is not available in devices with low flash memory

fs.readdir

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Call type:

require("fs").readdir(path)

Parameters

path - The path of the directory to list. If it is not supplied, '' is assumed, which will list the root directory

Returns

An array of filename strings (or undefined if the directory couldn't be listed)

Description

List all files in the supplied directory, returning them as an array of strings.

NOTE: Espruino does not yet support Async file IO, so this function behaves like the 'Sync' version.

fs.readdirSync

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Call type:

require("fs").readdirSync(path)

Parameters

path - The path of the directory to list. If it is not supplied, '' is assumed, which will list the root directory

Returns

An array of filename strings (or undefined if the directory couldn't be listed)

Description

List all files in the supplied directory, returning them as an array of strings.

Note: This is not available in devices with low flash memory

fs.readFile

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Call type:

require("fs").readFile(path)

Parameters

path - The path of the file to read

Returns

A string containing the contents of the file (or undefined if the file doesn't exist)

Description

Read all data from a file and return as a string

NOTE: Espruino does not yet support Async file IO, so this function behaves like the 'Sync' version.

fs.readFileSync

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Call type:

require("fs").readFileSync(path)

Parameters

path - The path of the file to read

Returns

A string containing the contents of the file (or undefined if the file doesn't exist)

Description

Read all data from a file and return as a string.

Note: The size of files you can load using this method is limited by the amount of available RAM. To read files a bit at a time, see the File class.

Note: This is not available in devices with low flash memory

fs.statSync

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Call type:

require("fs").statSync(path)

Parameters

path - The path of the file to get information on

Returns

An object describing the file, or undefined on failure

Description

Return information on the given file. This returns an object with the following fields:

size: size in bytes dir: a boolean specifying if the file is a directory or not mtime: A Date structure specifying the time the file was last modified

Note: This is not available in devices with low flash memory

fs.unlink

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Call type:

require("fs").unlink(path)

Parameters

path - The path of the file to delete

Returns

True on success, or false on failure

Description

Delete the given file

NOTE: Espruino does not yet support Async file IO, so this function behaves like the 'Sync' version.

Note: This is not available in devices with low flash memory

fs.unlinkSync

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Call type:

require("fs").unlinkSync(path)

Parameters

path - The path of the file to delete

Returns

True on success, or false on failure

Description

Delete the given file

Note: This is not available in devices with low flash memory

fs.writeFile

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Call type:

require("fs").writeFile(path, data)

Parameters

path - The path of the file to write

data - The data to write to the file

Returns

True on success, false on failure

Description

Write the data to the given file

NOTE: Espruino does not yet support Async file IO, so this function behaves like the 'Sync' version.

fs.writeFileSync

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Call type:

require("fs").writeFileSync(path, data)

Parameters

path - The path of the file to write

data - The data to write to the file

Returns

True on success, false on failure

Description

Write the data to the given file

Note: This is not available in devices with low flash memory

Function Class

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This is the built-in class for Functions

Methods and Fields

function Function.apply

View MDN documentation

(top)

Call type:

function Function.apply(this, args)

Parameters

this - The value to use as the 'this' argument when executing the function

args - Optional Array of Arguments

Returns

The return value of executing this function

Description

This executes the function with the supplied 'this' argument and parameters

function Function.bind

View MDN documentation

(top)

Call type:

function Function.bind(this, params, ...)

Parameters

this - The value to use as the 'this' argument when executing the function

params, ... - Optional Default parameters that are prepended to the call

Returns

The 'bound' function

Description

This executes the function with the supplied 'this' argument and parameters

function Function.call

View MDN documentation

(top)

Call type:

function Function.call(this, params, ...)

Parameters

this - The value to use as the 'this' argument when executing the function

params, ... - Optional Parameters

Returns

The return value of executing this function

Description

This executes the function with the supplied 'this' argument and parameters

constructor Function

View MDN documentation

(top)

Call type:

new Function(args, ...)

Parameters

args, ... - Zero or more arguments (as strings), followed by a string representing the code to run

Returns

A Number object

Description

Creates a function

function Function.replaceWith

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Call type:

function Function.replaceWith(newFunc)

Parameters

newFunc - The new function to replace this function with

Description

This replaces the function with the one in the argument - while keeping the old function's scope. This allows inner functions to be edited, and is used when edit() is called on an inner function.

Graphics Class

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This class provides Graphics operations that can be applied to a surface.

Use Graphics.createXXX to create a graphics object that renders in the way you want. See the Graphics page for more information.

Note: On boards that contain an LCD, there is a built-in g object of type Graphics. For instance to draw a line you'd type: g.drawLine(0,0,100,100)

Methods and Fields

function Graphics.asBMP

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Call type:

function Graphics.asBMP()

Returns

A String representing the Graphics as a Windows BMP file (or 'undefined' if not possible)

Description

Create a Windows BMP file from this Graphics instance, and return it as a String.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.asImage

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Call type:

function Graphics.asImage(type)

Parameters

type - The type of image to return. Either object/undefined to return an image object, or string to return an image string

Returns

An Image that can be used with Graphics.drawImage

Description

Return this Graphics object as an Image that can be used with Graphics.drawImage. Check out the Graphics reference page for more information on images.

Will return undefined if data can't be allocated for the image.

The image data itself will be referenced rather than copied if:

  • An image object was requested (not string)
  • The Graphics instance was created with Graphics.createArrayBuffer
  • Is 8 bpp OR the {msb:true} option was given
  • No other format options (zigzag/etc) were given

Otherwise data will be copied, which takes up more space and may be quite slow.

If the Graphics object contains transparent or palette fields, as you might find in an image, those will be included in the generated image too.


var gfx = Graphics.createArrayBuffer(8,8,1);
gfx.transparent = 0;
gfx.drawString("X",0,0);
var im = gfx.asImage("string");

Note: This is not available in devices with low flash memory

function Graphics.asURL

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Call type:

function Graphics.asURL()

Returns

A String representing the Graphics as a URL (or 'undefined' if not possible)

Description

Create a URL of the form data:image/bmp;base64,... that can be pasted into the browser.

The Espruino Web IDE can detect this data on the console and render the image inline automatically.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.blit

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Call type:

function Graphics.blit(options)

Parameters

options - options - see below

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Blit one area of the screen (x1,y1 w,h) to another (x2,y2 w,h)


g.blit({
  x1:0, y1:0,
  w:32, h:32,
  x2:100, y2:100,
  setModified : true // should we set the modified area?
});

Note: This uses repeated pixel reads and writes, so will not work on platforms that don't support pixel reads.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

property Graphics.buffer

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Call type:

property Graphics.buffer

Returns

An ArrayBuffer (or not defined on Graphics instances not created with Graphics.createArrayBuffer)

Description

On Graphics instances with an offscreen buffer, this is an ArrayBuffer that provides access to the underlying pixel data.


g=Graphics.createArrayBuffer(8,8,8)
g.drawLine(0,0,7,7)
print(new Uint8Array(g.buffer))
new Uint8Array([
255, 0, 0, 0, 0, 0, 0, 0,
0, 255, 0, 0, 0, 0, 0, 0,
0, 0, 255, 0, 0, 0, 0, 0,
0, 0, 0, 255, 0, 0, 0, 0,
0, 0, 0, 0, 255, 0, 0, 0,
0, 0, 0, 0, 0, 255, 0, 0,
0, 0, 0, 0, 0, 0, 255, 0,
0, 0, 0, 0, 0, 0, 0, 255])

function Graphics.clear

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Call type:

function Graphics.clear(reset)

Parameters

reset - [optional] If true, resets the state of Graphics to the default (eg. Color, Font, etc) as if calling Graphics.reset

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Clear the LCD with the Background Color

function Graphics.clearRect

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Call type:

function Graphics.clearRect(x1, y1, x2, y2)

Parameters

x1 - The left X coordinate OR an object containing {x,y,x2,y2} or {x,y,w,h}

y1 - The top Y coordinate

x2 - The right X coordinate

y2 - The bottom Y coordinate

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Fill a rectangular area in the Background Color

On devices with enough memory, you can specify {x,y,x2,y2,r} as the first argument, which allows you to draw a rounded rectangle.

Note: This is not available in devices with low flash memory

Graphics.createArrayBuffer

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Call type:

Graphics.createArrayBuffer(width, height, bpp, options)

Parameters

width - Pixels wide

height - Pixels high

bpp - Number of bits per pixel

options - An object of other options. { zigzag : true/false(default), vertical_byte : true/false(default), msb : true/false(default), color_order: 'rgb'(default),'bgr',etc }
zigzag = whether to alternate the direction of scanlines for rows
vertical_byte = whether to align bits in a byte vertically or not
msb = when bits<8, store pixels most significant bit first, when bits>8, store most significant byte first
interleavex = Pixels 0,2,4,etc are from the top half of the image, 1,3,5,etc from the bottom half. Used for P3 LED panels.
color_order = re-orders the colour values that are supplied via setColor

Returns

The new Graphics object

Description

Create a Graphics object that renders to an Array Buffer. This will have a field called 'buffer' that can get used to get at the buffer itself

Graphics.createCallback

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Call type:

Graphics.createCallback(width, height, bpp, callback)

Parameters

width - Pixels wide

height - Pixels high

bpp - Number of bits per pixel

callback - A function of the form function(x,y,col) that is called whenever a pixel needs to be drawn, or an object with: {setPixel:function(x,y,col),fillRect:function(x1,y1,x2,y2,col)}. All arguments are already bounds checked.

Returns

The new Graphics object

Description

Create a Graphics object that renders by calling a JavaScript callback function to draw pixels

Note: This is not available in devices with low flash memory

Graphics.createImage

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Call type:

Graphics.createImage(str)

Parameters

str - A String containing a newline-separated image - space/. is 0, anything else is 1

Returns

An Image object that can be used with Graphics.drawImage

Description

Create a simple Black and White image for use with Graphics.drawImage.

Use as follows:


var img = Graphics.createImage(`
XXXXXXXXX
X       X
X   X   X
X   X   X
X       X
XXXXXXXXX
`);
g.drawImage(img, x,y);
var img = Graphics.createImage(`
.....
.XXX.
.X.X.
.XXX.
.....
`);
g.drawImage(img, x,y);

If the characters at the beginning and end of the string are newlines, they will be ignored. Spaces are treated as 0, and any other character is a 1

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.drawCircle

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Call type:

function Graphics.drawCircle(x, y, rad)

Parameters

x - The X axis

y - The Y axis

rad - The circle radius

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw an unfilled circle 1px wide in the Foreground Color

Note: This is not available in devices with low flash memory

function Graphics.drawEllipse

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Call type:

function Graphics.drawEllipse(x1, y1, x2, y2)

Parameters

x1 - The left X coordinate

y1 - The top Y coordinate

x2 - The right X coordinate

y2 - The bottom Y coordinate

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw an ellipse in the Foreground Color

Note: This is not available in devices with low flash memory

function Graphics.drawImage

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Call type:

function Graphics.drawImage(image, x, y, options)

Parameters

image - An image to draw, either a String or an Object (see below)

x - The X offset to draw the image

y - The Y offset to draw the image

options - options for scaling,rotation,etc (see below)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Image can be:

  • An object with the following fields
    { width : int, height : int, bpp :
    optional int, buffer : ArrayBuffer/String, transparent: optional int,
    palette : optional Uint16Array(2/4/16) }
    . bpp = bits per pixel (default is 1), transparent (if defined) is the colour that will be treated as transparent, and palette is a color palette that each pixel will be looked up in first
  • A String where the the first few bytes are: width,height,bpp,[transparent,]image_bytes.... If a transparent colour is specified the top bit of bpp should be set.
  • An ArrayBuffer Graphics object (if bpp<8, msb:true must be set) - this is disabled on devices without much flash memory available. If a Graphics object is supplied, it can also contain transparent/palette fields as if it were an image.

See https://www.espruino.com/Graphics#images-bitmaps for more information about image formats.

Draw an image at the specified position.

  • If the image is 1 bit, the graphics foreground/background colours will be used.
  • If img.palette is a Uint16Array or 2/4/16 elements, color data will be looked from the supplied palette
  • On Bangle.js, 2 bit images blend from background(0) to foreground(1) colours
  • On Bangle.js, 4 bit images use the Apple Mac 16 color palette
  • On Bangle.js, 8 bit images use the Web Safe 216 color palette
  • Otherwise color data will be copied as-is. Bitmaps are rendered MSB-first

If options is supplied, drawImage will allow images to be rendered at any scale or angle. If options.rotate is set it will center images at x,y. options must be an object of the form:


{
  rotate : float, // the amount to rotate the image in radians (default 0)
  scale : float, // the amount to scale the image up (default 1)
  frame : int    // if specified and the image has frames of data
                 //  after the initial frame, draw one of those frames from the image
  filter : bool  // (2v19+) when set, if scale<0.75 perform 2x2 supersampling to smoothly downscale the image
}

For example:


// In the top left of the screen
g.drawImage(img,0,0);
// In the top left of the screen, twice as big
g.drawImage(img,0,0,{scale:2});
// In the center of the screen, twice as big, 45 degrees
g.drawImage(img, g.getWidth()/2, g.getHeight()/2,
            {scale:2, rotate:Math.PI/4});

function Graphics.drawLine

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Call type:

function Graphics.drawLine(x1, y1, x2, y2)

Parameters

x1 - The left

y1 - The top

x2 - The right

y2 - The bottom

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a line between x1,y1 and x2,y2 in the current foreground color

function Graphics.drawPoly

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Call type:

function Graphics.drawPoly(poly, closed)

Parameters

poly - An array of vertices, of the form [x1,y1,x2,y2,x3,y3,etc]

closed - Draw another line between the last element of the array and the first

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a polyline (lines between each of the points in poly) in the current foreground color

Note: there is a limit of 64 points (128 XY elements) for polygons

Note: This is not available in devices with low flash memory

function Graphics.drawRect

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Call type:

function Graphics.drawRect(x1, y1, x2, y2)

Parameters

x1 - The left X coordinate OR an object containing {x,y,x2,y2} or {x,y,w,h}

y1 - The top Y coordinate

x2 - The right X coordinate

y2 - The bottom Y coordinate

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw an unfilled rectangle 1px wide in the Foreground Color

function Graphics.drawString

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Call type:

function Graphics.drawString(str, x, y, solid)

Parameters

str - The string

x - The X position of the leftmost pixel

y - The Y position of the topmost pixel

solid - For bitmap fonts, should empty pixels be filled with the background color?

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a string of text in the current font.


g.drawString("Hello World", 10, 10);

Images may also be embedded inside strings (e.g. to render Emoji or characters not in the current font). To do this, just add 0 then the image string (about Images) For example:


g.drawString("Hi \0\7\5\1\x82 D\x17\xC0");
// draws:
// # #  #      #     #
// # #            #
// ### ##         #
// # #  #      #     #
// # # ###      #####

function Graphics.dump

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Call type:

function Graphics.dump()

Description

Output this image as a bitmap URL of the form data:image/bmp;base64,.... The Espruino Web IDE will detect this on the console and will render the image inline automatically.

This is identical to console.log(g.asURL()) - it is just a convenient function for easy debugging and producing screenshots of what is currently in the Graphics instance.

Note: This may not work on some bit depths of Graphics instances. It will also not work for the main Graphics instance of Bangle.js 1 as the graphics on Bangle.js 1 are stored in write-only memory.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.fillCircle

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Call type:

function Graphics.fillCircle(x, y, rad)

Parameters

x - The X axis

y - The Y axis

rad - The circle radius

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a filled circle in the Foreground Color

Note: This is not available in devices with low flash memory

function Graphics.fillEllipse

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Call type:

function Graphics.fillEllipse(x1, y1, x2, y2)

Parameters

x1 - The left X coordinate

y1 - The top Y coordinate

x2 - The right X coordinate

y2 - The bottom Y coordinate

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a filled ellipse in the Foreground Color

Note: This is not available in devices with low flash memory

function Graphics.fillPoly

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Call type:

function Graphics.fillPoly(poly)

Parameters

poly - An array of vertices, of the form [x1,y1,x2,y2,x3,y3,etc]

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a filled polygon in the current foreground color.


g.fillPoly([
  16, 0,
  31, 31,
  26, 31,
  16, 12,
  6, 28,
  0, 27 ]);

This fills from the top left hand side of the polygon (low X, low Y) down to but not including the bottom right. When placed together polygons will align perfectly without overdraw - but this will not fill the same pixels as drawPoly (drawing a line around the edge of the polygon).

Note: there is a limit of 64 points (128 XY elements) for polygons

Note: This is not available in devices with low flash memory

function Graphics.fillRect

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Call type:

function Graphics.fillRect(x1, y1, x2, y2)

Parameters

x1 - The left X coordinate OR an object containing {x,y,x2,y2} or {x,y,w,h}

y1 - The top Y coordinate

x2 - The right X coordinate

y2 - The bottom Y coordinate

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Fill a rectangular area in the Foreground Color

On devices with enough memory, you can specify {x,y,x2,y2,r} as the first argument, which allows you to draw a rounded rectangle.

function Graphics.flip

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Call type:

function Graphics.flip(all)

Parameters

all - [optional] (only on some devices) If true then copy all pixels, not just those that have changed.

Description

On instances of graphics that drive a display with an offscreen buffer, calling this function will copy the contents of the offscreen buffer to the screen.

Call this when you have drawn something to Graphics and you want it shown on the screen.

If a display does not have an offscreen buffer, it may not have a g.flip() method.

On Bangle.js 1, there are different graphics modes chosen with Bangle.setLCDMode(). The default mode is unbuffered and in this mode g.flip() does not affect the screen contents.

On some devices, this command will attempt to only update the areas of the screen that have changed in order to increase speed. If you have accessed the Graphics.buffer directly then you may need to use Graphics.flip(true) to force a full update of the screen.

function Graphics.floodFill

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Call type:

function Graphics.floodFill(x, y, col)

Parameters

x - X coordinate to start from

y - Y coordinate to start from

col - The color to fill with (if undefined, foreground is used)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Flood fills the given Graphics instance out from a particular point.

Note: This only works on Graphics instances that support readback with getPixel. It is also not capable of filling over dithered patterns (eg non-solid colours on Bangle.js 2)

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.getBgColor

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Call type:

function Graphics.getBgColor()

Returns

The integer value of the colour

Description

Get the background color to use for subsequent drawing operations

function Graphics.getBPP

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Call type:

function Graphics.getBPP()

Returns

The bits per pixel of this Graphics instance

Description

The number of bits per pixel of this Graphics instance

Note: Bangle.js 2 behaves a little differently here. The display is 3 bit, so getBPP returns 3 and asBMP/asImage/etc return 3 bit images. However in order to allow dithering, the colors returned by Graphics.getColor and Graphics.theme are actually 16 bits.

function Graphics.getColor

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Call type:

function Graphics.getColor()

Returns

The integer value of the colour

Description

Get the color to use for subsequent drawing operations

function Graphics.getFont

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Call type:

function Graphics.getFont()

Returns

Get the name of the current font

Description

Get the font by name - can be saved and used with Graphics.setFont.

Normally this might return something like "4x6", but if a scale factor is specified, a colon and then the size is reported, like "4x6:2"

Note: For custom fonts, Custom is currently reported instead of the font name.

Note: This is not available in devices with low flash memory

function Graphics.getFontHeight

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Call type:

function Graphics.getFontHeight()

Returns

The height in pixels of the current font

Description

Return the height in pixels of the current font

Note: This is not available in devices with low flash memory

function Graphics.getFonts

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Call type:

function Graphics.getFonts()

Returns

And array of font names

Description

Return an array of all fonts currently in the Graphics library.

Note: Vector fonts are specified as Vector# where # is the font height. As there are effectively infinite fonts, just Vector is included in the list.

Note: This is not available in devices with low flash memory

function Graphics.getHeight

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Call type:

function Graphics.getHeight()

Returns

The height of this Graphics instance

Description

The height of this Graphics instance

Graphics.getInstance

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Call type:

Graphics.getInstance()

Returns

An instance of Graphics or undefined

Description

On devices like Pixl.js or HYSTM boards that contain a built-in display this will return an instance of the graphics class that can be used to access that display.

Internally, this is stored as a member called gfx inside the 'hiddenRoot'.

function Graphics.getModified

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Call type:

function Graphics.getModified(reset)

Parameters

reset - Whether to reset the modified area or not

Returns

An object {x1,y1,x2,y2} containing the modified area, or undefined if not modified

Description

Return the area of the Graphics canvas that has been modified, and optionally clear the modified area to 0.

For instance if g.setPixel(10,20) was called, this would return

{x1:10,
y1:20, x2:10, y2:20}

Note: This is not available in devices with low flash memory

function Graphics.getPixel

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Call type:

function Graphics.getPixel(x, y)

Parameters

x - The left

y - The top

Returns

The color

Description

Get a pixel's color

function Graphics.getVectorFontPolys

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Call type:

function Graphics.getVectorFontPolys(str, options)

Parameters

str - The string

options - [optional] {x,y,w,h} (see below)

Returns

An array of Uint8Arrays for vector font polygons

Description

Return the current string as a series of polygons (using the current vector font). options is as follows:

  • x - X offset of font (default 0)
  • y - Y offset of font (default 0)
  • w - Width of font (default 256) - the actual width will likely be less than this as most characters are non-square
  • h - Height of font (default 256) - the actual height will likely be less than this as most characters don't fully fill the font box


g.getVectorFontPolys("Hi", {x:-80,y:-128});

Note: This is not available in devices with low flash memory and not NOVECTORFONT

function Graphics.getWidth

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Call type:

function Graphics.getWidth()

Returns

The width of this Graphics instance

Description

The width of this Graphics instance

function Graphics.imageMetrics

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Call type:

function Graphics.imageMetrics(str)

Parameters

str - The string

Returns

An object containing {width,height,bpp,transparent} for the image

Description

Return the width and height in pixels of an image (either Graphics, Image Object, Image String or ArrayBuffer). Returns undefined if image couldn't be decoded.

frames is also included is the image contains more information than you'd expect for a single bitmap. In this case the bitmap might be an animation with multiple frames

function Graphics.lineTo

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Call type:

function Graphics.lineTo(x, y)

Parameters

x - X value

y - Y value

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Draw a line from the last position of lineTo or moveTo to this position

function Graphics.moveTo

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Call type:

function Graphics.moveTo(x, y)

Parameters

x - X value

y - Y value

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Move the cursor to a position - see lineTo

function Graphics.quadraticBezier

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Call type:

function Graphics.quadraticBezier(arr, options)

Parameters

arr - An array of three vertices, six enties in form of [x0,y0,x1,y1,x2,y2]

options - number of points to calulate

Returns

Array with calculated points

Description

Calculate the square area under a Bezier curve.

x0,y0: start point x1,y1: control point y2,y2: end point

Max 10 points without start point.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.reset

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Call type:

function Graphics.reset()

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Reset the state of Graphics to the defaults (e.g. Color, Font, etc) that would have been used when Graphics was initialised.

function Graphics.scroll

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Call type:

function Graphics.scroll(x, y)

Parameters

x - X direction. >0 = to right

y - Y direction. >0 = down

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Scroll the contents of this graphics in a certain direction. The remaining area is filled with the background color.

Note: This uses repeated pixel reads and writes, so will not work on platforms that don't support pixel reads.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.setBgColor

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Call type:

function Graphics.setBgColor(r, g, b)

Parameters

r - Red (between 0 and 1) OR* an integer representing the color in the current bit depth and color order *OR a hexidecimal color string of the form '#012345'

g - Green (between 0 and 1)

b - Blue (between 0 and 1)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set the background color to use for subsequent drawing operations.

See Graphics.setColor for more information on the mapping of r, g, and b to pixel values.

Note:* On devices with low flash memory, r *must be an integer representing the color in the current bit depth. It cannot be a floating point value, and g and b are ignored.

function Graphics.setClipRect

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Call type:

function Graphics.setClipRect(x1, y1, x2, y2)

Parameters

x1 - Top left X coordinate

y1 - Top left Y coordinate

x2 - Bottom right X coordinate

y2 - Bottom right Y coordinate

Returns

The instance of Graphics this was called on, to allow call chaining

Description

This sets the 'clip rect' that subsequent drawing operations are clipped to sit between.

These values are inclusive - e.g. g.setClipRect(1,0,5,0) will ensure that only pixel rows 1,2,3,4,5 are touched on column 0.

Note: For maximum flexibility on Bangle.js 1, the values here are not range checked. For normal use, X and Y should be between 0 and getWidth()-1/getHeight()-1.

Note: The x/y values here are rotated, so that if Graphics.setRotation is used they correspond to the coordinates given to the draw functions, not to the physical device pixels.

Note: This is not available in devices with low flash memory

function Graphics.setColor

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Call type:

function Graphics.setColor(r, g, b)

Parameters

r - Red (between 0 and 1) OR* an integer representing the color in the current bit depth and color order *OR a hexidecimal color string of the form '#012345'

g - [optional] Green (between 0 and 1)

b - [optional] Blue (between 0 and 1)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set the color to use for subsequent drawing operations.

If just r is specified as an integer, the numeric value will be written directly into a pixel. eg. On a 24 bit Graphics instance you set bright blue with either g.setColor(0,0,1) or g.setColor(0x0000FF).

A good shortcut to ensure you get white on all platforms is to use g.setColor(-1)

The mapping is as follows:

  • 32 bit: r,g,b => 0xFFrrggbb
  • 24 bit: r,g,b => 0xrrggbb
  • 16 bit: r,g,b => 0brrrrrggggggbbbbb (RGB565)
  • Other bpp: r,g,b => white if r+g+b > 50%, otherwise black (use r on its own as an integer)

If you specified color_order when creating the Graphics instance, r,g and b will be swapped as you specified.

Note:* On devices with low flash memory, r *must be an integer representing the color in the current bit depth. It cannot be a floating point value, and g and b are ignored.

function Graphics.setFont

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Call type:

function Graphics.setFont(name, size)

Parameters

name - The name of the font to use (if undefined, the standard 4x6 font will be used)

size - The size of the font (or undefined)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set the font by name. Various forms are available:

  • g.setFont("4x6") - standard 4x6 bitmap font
  • g.setFont("Vector:12") - vector font 12px high
  • g.setFont("4x6:2") - 4x6 bitmap font, doubled in size
  • g.setFont("6x8:2x3") - 6x8 bitmap font, doubled in width, tripled in height

You can also use these forms, but they are not recommended:

  • g.setFont("Vector12") - vector font 12px high
  • g.setFont("4x6",2) - 4x6 bitmap font, doubled in size

g.getFont() will return the current font as a String.

For a list of available font names, you can use g.getFonts().

Note: This is not available in devices with low flash memory

function Graphics.setFontAlign

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Call type:

function Graphics.setFontAlign(x, y, rotation)

Parameters

x - X alignment. -1=left (default), 0=center, 1=right

y - Y alignment. -1=top (default), 0=center, 1=bottom

rotation - Rotation of the text. 0=normal, 1=90 degrees clockwise, 2=180, 3=270

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set the alignment for subsequent calls to drawString

Note: This is not available in devices with low flash memory

function Graphics.setFontBitmap

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Call type:

function Graphics.setFontBitmap()

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Make subsequent calls to drawString use the built-in 4x6 pixel bitmapped Font

It is recommended that you use Graphics.setFont("4x6") for more flexibility.

function Graphics.setFontCustom

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Call type:

function Graphics.setFontCustom(bitmap, firstChar, width, height)

Parameters

bitmap - A column-first, MSB-first, 1bpp bitmap containing the font bitmap

firstChar - The first character in the font - usually 32 (space)

width - The width of each character in the font. Either an integer, or a string where each character represents the width

height - The height as an integer (max 255). Bits 8-15 represent the scale factor (eg. 2<<8 is twice the size). Bits 16-23 represent the BPP (0,1=1 bpp, 2=2 bpp, 4=4 bpp)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Make subsequent calls to drawString use a Custom Font of the given height. See the Fonts page for more information about custom fonts and how to create them.

For examples of use, see the font modules.

Note: while you can specify the character code of the first character with firstChar, the newline character 13 will always be treated as a newline and not rendered.

Note: This is not available in devices with low flash memory

function Graphics.setFontPBF

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Call type:

function Graphics.setFontPBF(file, scale)

Parameters

file - The font as a PBF file

scale - The scale factor, default=1 (2=2x size)

Returns

The instance of Graphics this was called on, to allow call chaining

function Graphics.setFontVector

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Call type:

function Graphics.setFontVector(size)

Parameters

size - The height of the font, as an integer

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Make subsequent calls to drawString use a Vector Font of the given height.

It is recommended that you use Graphics.setFont("Vector", size) for more flexibility.

Note: This is not available in devices with low flash memory

function Graphics.setPixel

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Call type:

function Graphics.setPixel(x, y, col)

Parameters

x - The left

y - The top

col - The color (if undefined, the foreground color is useD)

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set a pixel's color

function Graphics.setRotation

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Call type:

function Graphics.setRotation(rotation, reflect)

Parameters

rotation - The clockwise rotation. 0 for no rotation, 1 for 90 degrees, 2 for 180, 3 for 270

reflect - Whether to reflect the image

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set the current rotation of the graphics device.

function Graphics.setTheme

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Call type:

function Graphics.setTheme(theme)

Parameters

theme - An object of the form returned by Graphics.theme

Returns

The instance of Graphics this was called on, to allow call chaining

Description

Set the global colour scheme. On Bangle.js, this is reloaded from settings.json for each new app loaded.

See Graphics.theme for the fields that can be provided. For instance you can change the background to red using:


g.setTheme({bg:"#f00"});

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.stringMetrics

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Call type:

function Graphics.stringMetrics(str)

Parameters

str - The string

Returns

An object containing {width,height,etc} for the string - see below

Description

Return the width and height in pixels of a string of text in the current font. The object returned contains:

JS
{
  width,              // Width of the string in pixels
  height,             // Height of the string in pixels
  unrenderableChars,  // If true, the string contains characters that the current font isn't able to render.
  imageCount,         // How many inline images are in this string?
  maxImageHeight,     // If there are images, what is the maximum height of all images?
}

function Graphics.stringWidth

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Call type:

function Graphics.stringWidth(str)

Parameters

str - The string

Returns

The length of the string in pixels

Description

Return the size in pixels of a string of text in the current font

property Graphics.theme

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Call type:

property Graphics.theme

Returns

An object containing the current 'theme' (see below)

Description

Returns an object of the form:


{
  fg : 0xFFFF,  // foreground colour
  bg : 0,       // background colour
  fg2 : 0xFFFF,  // accented foreground colour
  bg2 : 0x0007,  // accented background colour
  fgH : 0xFFFF,  // highlighted foreground colour
  bgH : 0x02F7,  // highlighted background colour
  dark : true,  // Is background dark (e.g. foreground should be a light colour)
}

These values can then be passed to g.setColor/g.setBgColor for example g.setColor(g.theme.fg2). When the Graphics instance is reset, the background color is automatically set to g.theme.bg and foreground is set to g.theme.fg.

On Bangle.js these values can be changed by writing updated values to theme in settings.js and reloading the app - or they can be changed temporarily by calling Graphics.setTheme

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.toColor

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Call type:

function Graphics.toColor(r, g, b)

Parameters

r - Red (between 0 and 1) OR* an integer representing the color in the current bit depth and color order *OR a hexidecimal color string of the form '#rrggbb' or'#rgb'`

g - Green (between 0 and 1)

b - Blue (between 0 and 1)

Returns

The color index represented by the arguments

Description

Work out the color value to be used in the current bit depth based on the arguments.

This is used internally by setColor and setBgColor


// 1 bit
g.toColor(1,1,1) => 1
// 16 bit
g.toColor(1,0,0) => 0xF800

Note: This is not available in devices with low flash memory

function Graphics.transformVertices

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Call type:

function Graphics.transformVertices(verts, transformation)

Parameters

verts - An array of vertices, of the form [x1,y1,x2,y2,x3,y3,etc]

transformation - The transformation to apply, either an Object or an Array (see below)

Returns

Array of transformed vertices

Description

Transformation can be:

  • An object of the form
    
    {
    x: float, // x offset (default 0)
    y: float, // y offset (default 0)
    scale: float, // scale factor (default 1)
    rotate: float, // angle in radians (default 0)
    }
    
  • A six-element array of the form [a,b,c,d,e,f], which represents the 2D transformation matrix

    
    a c e
    b d f
    0 0 1
    

    Apply a transformation to an array of vertices.

Note: This is not available in devices with low flash memory or 'Original' Espruino boards

function Graphics.wrapString

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Call type:

function Graphics.wrapString(str, maxWidth)

Parameters

str - The string

maxWidth - The width in pixels

Returns

An array of lines that are all less than maxWidth

Description

Wrap a string to the given pixel width using the current font, and return the lines as an array.

To render within the screen's width you can do:


g.drawString(g.wrapString(text, g.getWidth()).join("\n")),

heatshrink Library

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Simple library for compression/decompression using heatshrink, an LZSS compression tool.

Espruino uses heatshrink internally to compress RAM down to fit in Flash memory when save() is used. This just exposes that functionality.

Functions here take and return buffers of data. There is no support for streaming, so both the compressed and decompressed data must be able to fit in memory at the same time.


var c = require("heatshrink").compress("Hello World");
// =new Uint8Array([....]).buffer
var d = require("heatshrink").decompress(c);
// =new Uint8Array([72, 101, ...]).buffer
E.toString(d)
// ="Hello World"

If you'd like a way to perform compression/decompression on desktop, check out https://github.com/espruino/EspruinoWebTools#heatshrinkjs

Methods and Fields

heatshrink.compress

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Call type:

require("heatshrink").compress(data)

Parameters

data - The data to compress

Returns

Returns the result as an ArrayBuffer

Description

Compress the data supplied as input, and return heatshrink encoded data as an ArrayBuffer.

No type information is stored, and the data argument is treated as an array of bytes (whether it is a String/Uint8Array or even Uint16Array), so the result of decompressing any compressed data will always be an ArrayBuffer.

If you'd like a way to perform compression/decompression on desktop, check out https://github.com/espruino/EspruinoWebTools#heatshrinkjs

Note: This is not available in devices with low flash memory

heatshrink.decompress

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Call type:

require("heatshrink").decompress(data)

Parameters

data - The data to decompress

Returns

Returns the result as an ArrayBuffer

Description

Decompress the heatshrink-encoded data supplied as input, and return it as an ArrayBuffer.

To get the result as a String, wrap require("heatshrink").decompress in E.toString: E.toString(require("heatshrink").decompress(...))

If you'd like a way to perform compression/decompression on desktop, check out https://github.com/espruino/EspruinoWebTools#heatshrinkjs

Note: This is not available in devices with low flash memory

http Library

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This library allows you to create http servers and make http requests

In order to use this, you will need an extra module to get network connectivity such as the TI CC3000 or WIZnet W5500.

This is designed to be a cut-down version of the node.js library. Please see the Internet page for more information on how to use it.

Methods and Fields

http.createServer

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Call type:

require("http").createServer(callback)

Parameters

callback - A function(request,response) that will be called when a connection is made

Returns

Returns a new httpSrv object

Description

Create an HTTP Server

When a request to the server is made, the callback is called. In the callback you can use the methods on the response (httpSRs) to send data. You can also add request.on('data',function() { ... }) to listen for POSTed data

http.get

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Call type:

require("http").get(options, callback)

Parameters

options - A simple URL, or an object containing host,port,path,method fields

callback - A function(res) that will be called when a connection is made. You can then call res.on('data', function(data) { ... }) and res.on('close', function() { ... }) to deal with the response.

Returns

Returns a new httpCRq object

Description

Request a webpage over HTTP - a convenience function for http.request() that makes sure the HTTP command is 'GET', and that calls end automatically.


require("http").get("http://pur3.co.uk/hello.txt", function(res) {
  res.on('data', function(data) {
    console.log("HTTP> "+data);
  });
  res.on('close', function(data) {
    console.log("Connection closed");
  });
});

See http.request() and the Internet page and ` for more usage examples.

http.request

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Call type:

require("http").request(options, callback)

Parameters

options - An object containing host,port,path,method,headers fields (and also ca,key,cert if HTTPS is enabled)

callback - A function(res) that will be called when a connection is made. You can then call res.on('data', function(data) { ... }) and res.on('close', function() { ... }) to deal with the response.

Returns

Returns a new httpCRq object

Description

Create an HTTP Request - end() must be called on it to complete the operation. options is of the form:


var options = {
    host: 'example.com', // host name
    port: 80,            // (optional) port, defaults to 80
    path: '/',           // path sent to server
    method: 'GET',       // HTTP command sent to server (must be uppercase 'GET', 'POST', etc)
    protocol: 'http:',   // optional protocol - https: or http:
    headers: { key : value, key : value } // (optional) HTTP headers
  };
var req = require("http").request(options, function(res) {
  res.on('data', function(data) {
    console.log("HTTP> "+data);
  });
  res.on('close', function(data) {
    console.log("Connection closed");
  });
});
// You can req.write(...) here if your request requires data to be sent.
req.end(); // called to finish the HTTP request and get the response

You can easily pre-populate options from a URL using

var options =
url.parse("http://www.example.com/foo.html")

There's an example of using http.request for HTTP POST here

Note: if TLS/HTTPS is enabled, options can have ca, key and cert fields. See tls.connect for more information about these and how to use them.

httpCRq Class

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The HTTP client request, returned by http.request() and http.get().

Methods and Fields

event httpCRq.drain

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Call type:

httpCRq.on('drain', function() { ... });

Description

An event that is fired when the buffer is empty and it can accept more data to send.

function httpCRq.end

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Call type:

function httpCRq.end(data)

Parameters

data - A string containing data to send

Description

Finish this HTTP request - optional data to append as an argument

See Socket.write for more information about the data argument

event httpCRq.error

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Call type:

httpCRq.on('error', function() { ... });

Description

An event that is fired if there is an error making the request and the response callback has not been invoked. In this case the error event concludes the request attempt. The error event function receives an error object as parameter with a code field and a message field.

function httpCRq.write

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Call type:

function httpCRq.write(data)

Parameters

data - A string containing data to send

Returns

For node.js compatibility, returns the boolean false. When the send buffer is empty, a drain event will be sent

Description

This function writes the data argument as a string. Data that is passed in (including arrays) will be converted to a string with the normal JavaScript toString method. For more information about sending binary data see Socket.write

httpCRs Class

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The HTTP client response, passed to the callback of http.request() an http.get().

Methods and Fields

function httpCRs.available

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Call type:

function httpCRs.available()

Returns

How many bytes are available

Description

Return how many bytes are available to read. If there is a 'data' event handler, this will always return 0.

event httpCRs.close

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Call type:

httpCRs.on('close', function() { ... });

Description

Called when the connection closes with one hadError boolean parameter, which indicates whether an error occurred.

event httpCRs.data

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Call type:

httpCRs.on('data', function(data) { ... });

Parameters

data - A string containing one or more characters of received data

Description

The 'data' event is called when data is received. If a handler is defined with X.on('data', function(data) { ... }) then it will be called, otherwise data will be stored in an internal buffer, where it can be retrieved with X.read()

event httpCRs.error

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Call type:

httpCRs.on('error', function() { ... });

Description

An event that is fired if there is an error receiving the response. The error event function receives an error object as parameter with a code field and a message field. After the error event the close even will also be triggered to conclude the HTTP request/response.

property httpCRs.headers

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Call type:

property httpCRs.headers

Returns

An object mapping header name to value

Description

The headers received along with the HTTP response

property httpCRs.httpVersion

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Call type:

property httpCRs.httpVersion

Returns

Th

Description

The HTTP version reported back by the server - usually "1.1"

function httpCRs.pipe

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Call type:

function httpCRs.pipe(destination, options)

Parameters

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=32, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this to a stream (an object with a 'write' method)

Note: This is not available in devices with low flash memory

function httpCRs.read

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Call type:

function httpCRs.read(chars)

Parameters

chars - The number of characters to read, or undefined/0 for all available

Returns

A string containing the required bytes.

Description

Return a string containing characters that have been received

property httpCRs.statusCode

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Call type:

property httpCRs.statusCode

Returns

The status code as a String

Description

The HTTP response's status code - usually "200" if all went well

property httpCRs.statusMessage

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Call type:

property httpCRs.statusMessage

Returns

An String Status Message

Description

The HTTP response's status message - Usually "OK" if all went well

httpSRq Class

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The HTTP server request

Methods and Fields

function httpSRq.available

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Call type:

function httpSRq.available()

Returns

How many bytes are available

Description

Return how many bytes are available to read. If there is already a listener for data, this will always return 0.

event httpSRq.close

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Call type:

httpSRq.on('close', function() { ... });

Description

Called when the connection closes.

event httpSRq.data

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Call type:

httpSRq.on('data', function(data) { ... });

Parameters

data - A string containing one or more characters of received data

Description

The 'data' event is called when data is received. If a handler is defined with X.on('data', function(data) { ... }) then it will be called, otherwise data will be stored in an internal buffer, where it can be retrieved with X.read()

property httpSRq.headers

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Call type:

property httpSRq.headers

Returns

An object mapping header name to value

Description

The headers to sent to the server with this HTTP request.

property httpSRq.method

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Call type:

property httpSRq.method

Returns

A string

Description

The HTTP method used with this request. Often "GET".

function httpSRq.pipe

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Call type:

function httpSRq.pipe(destination, options)

Parameters

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=32, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this to a stream (an object with a 'write' method)

Note: This is not available in devices with low flash memory

function httpSRq.read

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Call type:

function httpSRq.read(chars)

Parameters

chars - The number of characters to read, or undefined/0 for all available

Returns

A string containing the required bytes.

Description

Return a string containing characters that have been received

property httpSRq.url

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Call type:

property httpSRq.url

Returns

A string representing the URL

Description

The URL requested in this HTTP request, for instance:

  • "/" - the main page
  • "/favicon.ico" - the web page's icon

httpSRs Class

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The HTTP server response

Methods and Fields

event httpSRs.close

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Call type:

httpSRs.on('close', function() { ... });

Description

Called when the connection closes.

event httpSRs.drain

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Call type:

httpSRs.on('drain', function() { ... });

Description

An event that is fired when the buffer is empty and it can accept more data to send.

function httpSRs.end

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Call type:

function httpSRs.end(data)

Parameters

data - A string containing data to send

Description

See Socket.write for more information about the data argument

property httpSRs.headers

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Call type:

property httpSRs.headers

Returns

An object mapping header name to value

Description

The headers to send back along with the HTTP response.

The default contents are:


{
  "Connection": "close"
 }

function httpSRs.setHeader

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Call type:

function httpSRs.setHeader(name, value)

Parameters

name - The name of the header as a String

value - The value of the header as a String

Description

Set a value to send in the header of this HTTP response. This updates the httpSRs.headers property.

Any headers supplied to writeHead will overwrite any headers with the same name.

function httpSRs.write

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Call type:

function httpSRs.write(data)

Parameters

data - A string containing data to send

Returns

For node.js compatibility, returns the boolean false. When the send buffer is empty, a drain event will be sent

Description

This function writes the data argument as a string. Data that is passed in (including arrays) will be converted to a string with the normal JavaScript toString method. For more information about sending binary data see Socket.write

function httpSRs.writeHead

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Call type:

function httpSRs.writeHead(statusCode, headers)

Parameters

statusCode - The HTTP status code

headers - An object containing the headers

Description

Send the given status code and headers. If not explicitly called this will be done automatically the first time data is written to the response.

This cannot be called twice, or after data has already been sent in the response.

httpSrv Class

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The HTTP server created by require('http').createServer

Methods and Fields

function httpSrv.close

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Call type:

function httpSrv.close()

Description

Stop listening for new HTTP connections

function httpSrv.listen

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Call type:

function httpSrv.listen(port)

Parameters

port - The port to listen on

Returns

The HTTP server instance that 'listen' was called on

Description

Start listening for new HTTP connections on the given port

I2C Class

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This class allows use of the built-in I2C ports. Currently it allows I2C Master mode only.

All addresses are in 7 bit format. If you have an 8 bit address then you need to shift it one bit to the right.

Instances

  • I2C1 The first I2C port
  • I2C2 The second I2C port
  • I2C3 The third I2C port

Methods and Fields

I2C.find

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Call type:

I2C.find(pin)

Parameters

pin - A pin to search with

Returns

An object of type I2C, or undefined if one couldn't be found.

Description

Try and find an I2C hardware device that will work on this pin (e.g. I2C1)

May return undefined if no device can be found.

constructor I2C

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Call type:

new I2C()

Returns

An I2C object

Description

Create a software I2C port. This has limited functionality (no baud rate), but it can work on any pins.

Use I2C.setup to configure this port.

function I2C.readFrom

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Call type:

function I2C.readFrom(address, quantity)

Parameters

address - The 7 bit address of the device to request bytes from, or an object of the form {address:12, stop:false} to send this data without a STOP signal.

quantity - The number of bytes to request

Returns

The data that was returned - as a Uint8Array

Description

Request bytes from the given slave device, and return them as a Uint8Array (packed array of bytes). This is like using Arduino Wire's requestFrom, available and read functions. Sends a STOP unless {address:X, stop:false} is used.

function I2C.readReg

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Call type:

function I2C.readReg(address, reg, quantity)

Parameters

address - The 7 bit address of the device to request bytes from

reg - The register on the device to read bytes from

quantity - The number of bytes to request

Returns

The data that was returned - as a Uint8Array

Description

Request bytes from a register on the given I2C slave device, and return them as a Uint8Array (packed array of bytes).

This is the same as calling I2C.writeTo and I2C.readFrom:


I2C.readReg = function(address, reg, quantity) {
  this.writeTo({address:address, stop:false}, reg);
  return this.readFrom(address, quantity);
};

function I2C.setup

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Call type:

function I2C.setup(options)

Parameters

options - [optional] A structure containing extra information on initialising the I2C port
{scl:pin, sda:pin, bitrate:100000}
You can find out which pins to use by looking at your board's reference page and searching for pins with the I2C marker. Note that 400kHz is the maximum bitrate for most parts.

Description

Set up this I2C port

If not specified in options, the default pins are used (usually the lowest numbered pins on the lowest port that supports this peripheral)

function I2C.writeTo

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Call type:

function I2C.writeTo(address, data, ...)

Parameters

address - The 7 bit address of the device to transmit to, or an object of the form {address:12, stop:false} to send this data without a STOP signal.

data, ... - One or more items to write. May be ints, strings, arrays, or special objects (see E.toUint8Array for more info).

Description

Transmit to the slave device with the given address. This is like Arduino's beginTransmission, write, and endTransmission rolled up into one.

Int16Array Class

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This is the built-in JavaScript class for a typed array of 16 bit signed integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Int16Array

View MDN documentation

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Call type:

new Int16Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Int32Array Class

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This is the built-in JavaScript class for a typed array of 32 bit signed integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Int32Array

View MDN documentation

(top)

Call type:

new Int32Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Int8Array Class

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This is the built-in JavaScript class for a typed array of 8 bit signed integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Int8Array

View MDN documentation

(top)

Call type:

new Int8Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

InternalError Class

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The base class for internal errors

Methods and Fields

constructor InternalError

View MDN documentation

(top)

Call type:

new InternalError(message)

Parameters

message - [optional] An message string

Returns

An InternalError object

Description

Creates an InternalError object

function InternalError.toString

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Call type:

function InternalError.toString()

Returns

A String

JSON Class

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An Object that handles conversion to and from the JSON data interchange format

Methods and Fields

JSON.parse

View MDN documentation

(top)

Call type:

JSON.parse(string)

Parameters

string - A JSON string

Returns

The JavaScript object created by parsing the data string

Description

Parse the given JSON string into a JavaScript object

NOTE: This implementation uses eval() internally, and as such it is unsafe as it can allow arbitrary JS commands to be executed.

JSON.stringify

View MDN documentation

(top)

Call type:

JSON.stringify(data, replacer, space)

Parameters

data - The data to be converted to a JSON string

replacer - [optional] This value is ignored

space - [optional] The number of spaces to use for padding, a string, or null/undefined for no whitespace

Returns

A JSON string

Description

Convert the given object into a JSON string which can subsequently be parsed with JSON.parse or eval.

Note: This differs from JavaScript's standard JSON.stringify in that:

  • The replacer argument is ignored
  • Typed arrays like new Uint8Array(5) will be dumped as if they were arrays, not as if they were objects (since it is more compact)

Math Class

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This is a standard JavaScript class that contains useful Maths routines

Methods and Fields

Math.abs

View MDN documentation

(top)

Call type:

Math.abs(x)

Parameters

x - A floating point value

Returns

The absolute value of x (eg, Math.abs(2)==2, but also Math.abs(-2)==2)

Math.acos

View MDN documentation

(top)

Call type:

Math.acos(x)

Parameters

x - The value to get the arc cosine of

Returns

The arc cosine of x, between 0 and PI

Math.asin

View MDN documentation

(top)

Call type:

Math.asin(x)

Parameters

x - The value to get the arc sine of

Returns

The arc sine of x, between -PI/2 and PI/2

Math.atan

View MDN documentation

(top)

Call type:

Math.atan(x)

Parameters

x - The value to get the arc tangent of

Returns

The arc tangent of x, between -PI/2 and PI/2

Math.atan2

View MDN documentation

(top)

Call type:

Math.atan2(y, x)

Parameters

y - The Y-part of the angle to get the arc tangent of

x - The X-part of the angle to get the arc tangent of

Returns

The arctangent of Y/X, between -PI and PI

Math.ceil

View MDN documentation

(top)

Call type:

Math.ceil(x)

Parameters

x - The value to round up

Returns

x, rounded upwards to the nearest integer

Math.clip

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Call type:

Math.clip(x, min, max)

Parameters

x - A floating point value to clip

min - The smallest the value should be

max - The largest the value should be

Returns

The value of x, clipped so as not to be below min or above max.

Description

DEPRECATED - Please use E.clip() instead. Clip a number to be between min and max (inclusive)

Note: This is not available in devices with low flash memory

Math.cos

View MDN documentation

(top)

Call type:

Math.cos(theta)

Parameters

theta - The angle to get the cosine of

Returns

The cosine of theta

Math.E

View MDN documentation

(top)

Call type:

Math.E

Returns

The value of E - 2.718281828459045

Math.exp

View MDN documentation

(top)

Call type:

Math.exp(x)

Parameters

x - The value raise E to the power of

Returns

E^x

Math.floor

View MDN documentation

(top)

Call type:

Math.floor(x)

Parameters

x - The value to round down

Returns

x, rounded downwards to the nearest integer

Math.LN10

View MDN documentation

(top)

Call type:

Math.LN10

Returns

The natural logarithm of 10 - 2.302585092994046

Math.LN2

View MDN documentation

(top)

Call type:

Math.LN2

Returns

The natural logarithm of 2 - 0.6931471805599453

Math.log

View MDN documentation

(top)

Call type:

Math.log(x)

Parameters

x - The value to take the logarithm (base E) root of

Returns

The log (base E) of x

Math.LOG10E

View MDN documentation

(top)

Call type:

Math.LOG10E

Returns

The base 10 logarithm of e - 0.4342944819032518

Math.LOG2E

View MDN documentation

(top)

Call type:

Math.LOG2E

Returns

The base 2 logarithm of e - 1.4426950408889634

Math.max

View MDN documentation

(top)

Call type:

Math.max(args, ...)

Parameters

args, ... - Floating point values to clip

Returns

The maximum of the supplied values

Description

Find the maximum of a series of numbers

Math.min

View MDN documentation

(top)

Call type:

Math.min(args, ...)

Parameters

args, ... - Floating point values to clip

Returns

The minimum of the supplied values

Description

Find the minimum of a series of numbers

Math.PI

View MDN documentation

(top)

Call type:

Math.PI

Returns

The value of PI - 3.141592653589793

Math.pow

View MDN documentation

(top)

Call type:

Math.pow(x, y)

Parameters

x - The value to raise to the power

y - The power x should be raised to

Returns

x raised to the power y (x^y)

Math.random

View MDN documentation

(top)

Call type:

Math.random()

Returns

A random number between 0 and 1

Math.round

View MDN documentation

(top)

Call type:

Math.round(x)

Parameters

x - The value to round

Returns

x, rounded to the nearest integer

Math.sign

View MDN documentation

(top)

Call type:

Math.sign(x)

Parameters

x - The value to get the sign from

Returns

sign on x - -1, 1, or 0

Math.sin

View MDN documentation

(top)

Call type:

Math.sin(theta)

Parameters

theta - The angle to get the sine of

Returns

The sine of theta

Math.sqrt

View MDN documentation

(top)

Call type:

Math.sqrt(x)

Parameters

x - The value to take the square root of

Returns

The square root of x

Math.SQRT1_2

View MDN documentation

(top)

Call type:

Math.SQRT1_2

Returns

The square root of 1/2 - 0.7071067811865476

Math.SQRT2

View MDN documentation

(top)

Call type:

Math.SQRT2

Returns

The square root of 2 - 1.4142135623730951

Math.tan

View MDN documentation

(top)

Call type:

Math.tan(theta)

Parameters

theta - The angle to get the tangent of

Returns

The tangent of theta

Math.wrap

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Call type:

Math.wrap(x, max)

Parameters

x - A floating point value to wrap

max - The largest the value should be

Returns

The value of x, wrapped so as not to be below min or above max.

Description

DEPRECATED - This is not part of standard JavaScript libraries

Wrap a number around if it is less than 0 or greater than or equal to max. For instance you might do: Math.wrap(angleInDegrees, 360)

Note: This is not available in devices with low flash memory

Modules Class

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Built-in class that caches the modules used by the require command

Methods and Fields

Modules.addCached

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Call type:

Modules.addCached(id, sourcecode)

Parameters

id - The module name to add

sourcecode - The module's sourcecode

Description

Add the given module to the cache

Modules.getCached

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Call type:

Modules.getCached()

Returns

An array of module names

Description

Return an array of module names that have been cached

Modules.removeAllCached

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Call type:

Modules.removeAllCached()

Description

Remove all cached modules

Modules.removeCached

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Call type:

Modules.removeCached(id)

Parameters

id - The module name to remove

Description

Remove the given module from the list of cached modules

neopixel Library

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This library allows you to write to Neopixel/WS281x/APA10x/SK6812 LED strips

These use a high speed single-wire protocol which needs platform-specific implementation on some devices - hence this library to simplify things.

Methods and Fields

neopixel.write

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Call type:

require("neopixel").write(pin, data)

Parameters

pin - The Pin the LEDs are connected to

data - The data to write to the LED strip (must be a multiple of 3 bytes long)

Description

Write to a strip of NeoPixel/WS281x/APA104/APA106/SK6812-style LEDs attached to the given pin.


// set just one pixel, red, green, blue
require("neopixel").write(B15, [255,0,0]);


// Produce an animated rainbow over 25 LEDs
var rgb = new Uint8ClampedArray(25*3);
var pos = 0;
function getPattern() {
  pos++;
  for (var i=0;i<rgb.length;) {
    rgb[i++] = (1 + Math.sin((i+pos)*0.1324)) * 127;
    rgb[i++] = (1 + Math.sin((i+pos)*0.1654)) * 127;
    rgb[i++] = (1 + Math.sin((i+pos)*0.1)) * 127;
  }
  return rgb;
}
setInterval(function() {
  require("neopixel").write(B15, getPattern());
}, 100);

Note:

  • Different types of LED have the data in different orders - so don't be surprised by RGB or BGR orderings!

  • Some LED strips (SK6812) actually take 4 bytes per LED (red, green, blue and white). These are still supported but the array of data supplied must still be a multiple of 3 bytes long. Just round the size up - it won't cause any problems.

  • On some platforms like STM32, pins capable of hardware SPI MOSI are required.

  • On STM32, neopixel.write chooses a hardware SPI device to output the signal on and uses that. However in order to avoid spikes in the output, if that hardware device is already initialised it will not be re-initialised. This means that if the SPI device was already in use, you may have to use SPIx.setup({baud:3200000, mosi:the_pin}) to force it to be re-setup on the pin.

  • Espruino devices tend to have 3.3v IO, while WS2812/etc run off of 5v. Many WS2812 will only register a logic '1' at 70% of their input voltage - so if powering them off 5v you will not be able to send them data reliably. You can work around this by powering the LEDs off a lower voltage (for example 3.7v from a LiPo battery), can put the output into the af_opendrain state and use a pullup resistor to 5v on STM32 based boards (nRF52 are not 5v tolerant so you can't do this), or can use a level shifter to shift the voltage up into the 5v range.

net Library

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This library allows you to create TCPIP servers and clients

In order to use this, you will need an extra module to get network connectivity.

This is designed to be a cut-down version of the node.js library. Please see the Internet page for more information on how to use it.

Methods and Fields

net.connect

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Call type:

require("net").connect(options, callback)

Parameters

options - An object containing host,port fields

callback - A function(sckt) that will be called with the socket when a connection is made. You can then call sckt.write(...) to send data, and sckt.on('data', function(data) { ... }) and sckt.on('close', function() { ... }) to deal with the response.

Returns

Returns a new net.Socket object

Description

Create a TCP socket connection

net.createServer

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Call type:

require("net").createServer(callback)

Parameters

callback - A function(connection) that will be called when a connection is made

Returns

Returns a new Server Object

Description

Create a Server

When a request to the server is made, the callback is called. In the callback you can use the methods on the connection to send data. You can also add connection.on('data',function() { ... }) to listen for received data

NetworkJS Library

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Library that initialises a network device that calls into JavaScript

Methods and Fields

NetworkJS.create

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Call type:

require("NetworkJS").create(obj)

Parameters

obj - An object containing functions to access the network device

Returns

The object passed in

Description

Initialise the network using the callbacks given and return the first argument. For instance:


require("NetworkJS").create({
  create : function(host, port, socketType, options) {
    // Create a socket and return its index, host is a string, port is an integer.
    // If host isn't defined, create a server socket
    console.log("Create",host,port);
    return 1;
  },
  close : function(sckt) {
    // Close the socket. returns nothing
  },
  accept : function(sckt) {
    // Accept the connection on the server socket. Returns socket number or -1 if no connection
    return -1;
  },
  recv : function(sckt, maxLen, socketType) {
    // Receive data. Returns a string (even if empty).
    // If non-string returned, socket is then closed
    return null;//or "";
  },
  send : function(sckt, data, socketType) {
    // Send data (as string). Returns the number of bytes sent - 0 is ok.
    // Less than 0
    return data.length;
  }
});

socketType is an integer - 2 for UDP, or see SocketType in https://github.com/espruino/Espruino/blob/master/libs/network/network.h for more information.

Number Class

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This is the built-in JavaScript class for numbers.

Methods and Fields

Number.MAX_VALUE

View MDN documentation

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Call type:

Number.MAX_VALUE

Returns

Maximum representable value

Number.MIN_VALUE

View MDN documentation

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Call type:

Number.MIN_VALUE

Returns

Smallest representable value

Number.NaN

View MDN documentation

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Call type:

Number.NaN

Returns

Not a Number

Number.NEGATIVE_INFINITY

View MDN documentation

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Call type:

Number.NEGATIVE_INFINITY

Returns

Negative Infinity (-1/0)

constructor Number

View MDN documentation

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Call type:

new Number(value, ...)

Parameters

value, ... - A single value to be converted to a number

Returns

A Number object

Description

Creates a number

Number.POSITIVE_INFINITY

View MDN documentation

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Call type:

Number.POSITIVE_INFINITY

Returns

Positive Infinity (1/0)

function Number.toFixed

View MDN documentation

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Call type:

function Number.toFixed(decimalPlaces)

Parameters

decimalPlaces - A number between 0 and 20 specifying the number of decimal digits after the decimal point

Returns

A string

Description

Format the number as a fixed point number

Object Class

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This is the built-in class for Objects

Methods and Fields

function Object.addListener

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Call type:

function Object.addListener(event, listener)

Parameters

event - The name of the event, for instance 'data'

listener - The listener to call when this event is received

Description

Register an event listener for this object, for instance Serial1.addListener('data', function(d) {...}).

An alias for Object.on

Note: This is not available in Embeddable Espruino C builds

Object.assign

View MDN documentation

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Call type:

Object.assign(args, ...)

Parameters

args, ... - The target object, then any items objects to use as sources of keys

Returns

The target object

Description

Appends all keys and values in any subsequent objects to the first object

Note: Unlike the standard ES6 Object.assign, this will throw an exception if given raw strings, bools or numbers rather than objects.

function Object.clone

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Call type:

function Object.clone()

Returns

A copy of this Object

Description

Copy this object to a new object, but as a shallow copy. This has a similar effect to calling Object.assign({}, obj).


orig = { a : 1, b : [ 2, 3 ] }
copy = orig.clone();
// copy = { a : 1, b : [ 2, 3 ] }

Note: This is not a standard JavaScript function, but is unique to Espruino

Object.create

View MDN documentation

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Call type:

Object.create(proto, propertiesObject)

Parameters

proto - A prototype object

propertiesObject - An object containing properties. NOT IMPLEMENTED

Returns

A new object

Description

Creates a new object with the specified prototype object and properties. properties are currently unsupported.

Object.defineProperties

View MDN documentation

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Call type:

Object.defineProperties(obj, props)

Parameters

obj - An object

props - An object whose fields represent property names, and whose values are property descriptors.

Returns

The object, obj.

Description

Adds new properties to the Object. See Object.defineProperty for more information

Object.defineProperty

View MDN documentation

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Call type:

Object.defineProperty(obj, name, desc)

Parameters

obj - An object

name - The name of the property

desc - The property descriptor

Returns

The object, obj.

Description

Add a new property to the Object. 'Desc' is an object with the following fields:

  • configurable (bool = false) - can this property be changed/deleted (not implemented)
  • enumerable (bool = false) - can this property be enumerated (not implemented)
  • value (anything) - the value of this property
  • writable (bool = false) - can the value be changed with the assignment operator?
  • get (function) - the getter function, or undefined if no getter (only supported on some platforms)
  • set (function) - the setter function, or undefined if no setter (only supported on some platforms)

Note: configurable, enumerable and writable are not implemented and will be ignored.

function Object.emit

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Call type:

function Object.emit(event, args, ...)

Parameters

event - The name of the event, for instance 'data'

args, ... - Optional arguments

Description

Call any event listeners that were added to this object with Object.on, for instance obj.emit('data', 'Foo').

For more information see Object.on

Note: This is not available in Embeddable Espruino C builds

Object.entries

View MDN documentation

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Call type:

Object.entries(object)

Parameters

object - The object to return values for

Returns

An array of [key,value] pairs - one for each key on the given object

Description

Return all enumerable keys and values of the given object

Note: This is not available in devices with low flash memory

Object.fromEntries

View MDN documentation

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Call type:

Object.fromEntries(entries)

Parameters

entries - An array of [key,value] pairs to be used to create an object

Returns

An object containing all the specified pairs

Description

Transforms an array of key-value pairs into an object

Note: This is not available in devices with low flash memory

Object.getOwnPropertyDescriptor

View MDN documentation

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Call type:

Object.getOwnPropertyDescriptor(obj, name)

Parameters

obj - The object

name - The name of the property

Returns

An object with a description of the property. The values of writable/enumerable/configurable may not be entirely correct due to Espruino's implementation.

Description

Get information on the given property in the object, or undefined

Object.getOwnPropertyDescriptors

View MDN documentation

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Call type:

Object.getOwnPropertyDescriptors(obj)

Parameters

obj - The object

Returns

An object containing all the property descriptors of an object

Description

Get information on all properties in the object (from Object.getOwnPropertyDescriptor), or just {} if no properties

Note: This is not available in devices with low flash memory

Object.getOwnPropertyNames

View MDN documentation

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Call type:

Object.getOwnPropertyNames(object)

Parameters

object - The Object to return a list of property names for

Returns

An array of the Object's own properties

Description

Returns an array of all properties (enumerable or not) found directly on a given object.

Object.getPrototypeOf

View MDN documentation

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Call type:

Object.getPrototypeOf(object)

Parameters

object - An object

Returns

The prototype

Description

Get the prototype of the given object - this is like writing object.__proto__ but is the 'proper' ES6 way of doing it

function Object.hasOwnProperty

View MDN documentation

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Call type:

function Object.hasOwnProperty(name)

Parameters

name - The name of the property to search for

Returns

True if it exists, false if it doesn't

Description

Return true if the object (not its prototype) has the given property.

NOTE: This currently returns false-positives for built-in functions in prototypes

Object.keys

View MDN documentation

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Call type:

Object.keys(object)

Parameters

object - The object to return keys for

Returns

An array of strings - one for each key on the given object

Description

Return all enumerable keys of the given object

property Object.length

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Call type:

property Object.length

Returns

The length of the object

Description

Find the length of the object

constructor Object

View MDN documentation

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Call type:

new Object(value)

Parameters

value - A single value to be converted to an object

Returns

An Object

Description

Creates an Object from the supplied argument

function Object.on

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Call type:

function Object.on(event, listener)

Parameters

event - The name of the event, for instance 'data'

listener - The listener to call when this event is received

Description

Register an event listener for this object, for instance

Serial1.on('data',
function(d) {...})
.

This is the same as Node.js's EventEmitter but on Espruino the functionality is built into every object:


var o = {}; // o can be any object...
// call an arrow function when the 'answer' event is received
o.on('answer', x => console.log(x));
// call a named function when the 'answer' event is received
function printAnswer(d) {
  console.log("The answer is", d);
}
o.on('answer', printAnswer);
// emit the 'answer' event - functions added with 'on' will be executed
o.emit('answer', 42);
// prints: 42
// prints: The answer is 42
// If you have a named function, it can be removed by name
o.removeListener('answer', printAnswer);
// Now 'printAnswer' is removed
o.emit('answer', 43);
// prints: 43
// Or you can remove all listeners for 'answer'
o.removeAllListeners('answer')
// Now nothing happens
o.emit('answer', 44);
// nothing printed

If you have more than one handler for an event, and you'd like that handler to stop the event being passed to other handlers then you can call E.stopEventPropagation() in that handler.

Note: This is not available in Embeddable Espruino C builds

function Object.prependListener

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Call type:

function Object.prependListener(event, listener)

Parameters

event - The name of the event, for instance 'data'

listener - The listener to call when this event is received

Description

Register an event listener for this object, for instance Serial1.addListener('data', function(d) {...}).

An alias for Object.on

Note: This is not available in Embeddable Espruino C builds

function Object.removeAllListeners

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Call type:

function Object.removeAllListeners(event)

Parameters

event - [optional] The name of the event, for instance 'data'. If not specified all listeners are removed.

Description

Removes all listeners (if event===undefined), or those of the specified event.


Serial1.on("data", function(data) { ... });
Serial1.removeAllListeners("data");
// or
Serial1.removeAllListeners(); // removes all listeners for all event types

For more information see Object.on

function Object.removeListener

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Call type:

function Object.removeListener(event, listener)

Parameters

event - The name of the event, for instance 'data'

listener - The listener to remove

Description

Removes the specified event listener.


function foo(d) {
  console.log(d);
}
Serial1.on("data", foo);
Serial1.removeListener("data", foo);

For more information see Object.on

Object.setPrototypeOf

View MDN documentation

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Call type:

Object.setPrototypeOf(object, prototype)

Parameters

object - An object

prototype - The prototype to set on the object

Returns

The object passed in

Description

Set the prototype of the given object - this is like writing

object.__proto__ =
prototype
but is the 'proper' ES6 way of doing it

function Object.toString

View MDN documentation

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Call type:

function Object.toString(radix)

Parameters

radix - [optional] If the object is an integer, the radix (between 2 and 36) to use. NOTE: Setting a radix does not work on floating point numbers.

Returns

A String representing the object

Description

Convert the Object to a string

function Object.valueOf

View MDN documentation

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Call type:

function Object.valueOf()

Returns

The primitive value of this object

Description

Returns the primitive value of this object.

Object.values

View MDN documentation

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Call type:

Object.values(object)

Parameters

object - The object to return values for

Returns

An array of values - one for each key on the given object

Description

Return all enumerable values of the given object

Note: This is not available in devices with low flash memory

OneWire Class

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This class provides a software-defined OneWire master. It is designed to be similar to Arduino's OneWire library.

Note: OneWire commands are very timing-sensitive, and on nRF52 devices (Bluetooth LE Espruino boards) the bluetooth stack can get in the way. Before version 2v18 of Espruino OneWire could be unreliable, but as of firmware 2v18 Espruino now schedules OneWire accesses with the bluetooth stack to ensure it doesn't interfere. OneWire is now reliable but some functions such as OneWire.search can now take a while to execute (around 1 second).

Methods and Fields

constructor OneWire

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Call type:

new OneWire(pin)

Parameters

pin - The pin to implement OneWire on

Returns

A OneWire object

Description

Create a software OneWire implementation on the given pin

function OneWire.read

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Call type:

function OneWire.read(count)

Parameters

count - [optional] The amount of bytes to read

Returns

The byte that was read, or a Uint8Array if count was specified and >=0

Description

Read a byte

function OneWire.reset

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Call type:

function OneWire.reset()

Returns

True is a device was present (it held the bus low)

Description

Perform a reset cycle

function OneWire.search

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Call type:

function OneWire.search(command)

Parameters

command - (Optional) command byte. If not specified (or zero), this defaults to 0xF0. This can could be set to 0xEC to perform a DS18B20 'Alarm Search Command'

Returns

An array of devices that were found

Description

Search for devices

function OneWire.select

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Call type:

function OneWire.select(rom)

Parameters

rom - The device to select (get this using OneWire.search())

Description

Select a ROM - always performs a reset first

function OneWire.skip

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Call type:

function OneWire.skip()

Description

Skip a ROM

function OneWire.write

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Call type:

function OneWire.write(data, power)

Parameters

data - A byte (or array of bytes) to write

power - Whether to leave power on after write (default is false)

Description

Write one or more bytes

Pin Class

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This is the built-in class for Pins, such as D0,D1,LED1, or BTN

You can call the methods on Pin, or you can use Wiring-style functions such as digitalWrite

Methods and Fields

function Pin.analog

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Call type:

function Pin.analog()

Returns

The analog Value of the Pin between 0 and 1

Description

(Added in 2v20) Get the analogue value of the given pin. See analogRead for more information.

function Pin.getInfo

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Call type:

function Pin.getInfo()

Returns

An object containing information about this pins

Description

Get information about this pin and its capabilities. Of the form:


{
  "port"      : "A", // the Pin's port on the chip
  "num"       : 12, // the Pin's number
  "in_addr"   : 0x..., // (if available) the address of the pin's input address in bit-banded memory (can be used with peek)
  "out_addr"  : 0x..., // (if available) the address of the pin's output address in bit-banded memory (can be used with poke)
  "analog"    : { ADCs : [1], channel : 12 }, // If analog input is available
  "functions" : {
    "TIM1":{type:"CH1, af:0},
    "I2C3":{type:"SCL", af:1}
  }
}
Will return undefined if pin is not valid.

Note: This is not available in devices with low flash memory

function Pin.getMode

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Call type:

function Pin.getMode()

Returns

The pin mode, as a string

Description

Return the current mode of the given pin. See pinMode for more information.

function Pin.mode

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Call type:

function Pin.mode(mode)

Parameters

mode - The mode - a string that is either 'analog', 'input', 'inputpullup', 'inputpulldown', 'output', 'opendrain', 'afoutput' or 'afopendrain'. Do not include this argument if you want to revert to automatic pin mode setting.

Description

Set the mode of the given pin. See pinMode for more information on pin modes.

Pin.Pin

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Call type:

Pin.Pin()

Description

This is the built-in class for Pins, such as D0,D1,LED1, or BTN

You can call the methods on Pin, or you can use Wiring-style functions such as digitalWrite

constructor Pin

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Call type:

new Pin(value)

Parameters

value - A value to be converted to a pin. Can be a number, pin, or String.

Returns

A Pin object

Description

Creates a pin from the given argument (or returns undefined if no argument)

function Pin.pulse

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Call type:

function Pin.pulse(value, time)

Parameters

value - Whether to pulse high (true) or low (false)

time - A time in milliseconds, or an array of times (in which case a square wave will be output starting with a pulse of 'value')

Description

(Added in 2v20) Pulse the pin with the value for the given time in milliseconds.


LED.pulse(1, 100); // pulse LED on for 100ms
LED.pulse(1, [100,1000,100]); // pulse LED on for 100ms, off for 1s, on for 100ms

This is identical to digitalPulse.

function Pin.pwm

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Call type:

function Pin.pwm(value, options)

Parameters

value - A value between 0 and 1

options - An object containing options for analog output - see below

Description

(Added in 2v20) Set the analog Value of a pin. It will be output using PWM.

See analogWrite for more information.

Objects can contain:

  • freq - pulse frequency in Hz, e.g. analogWrite(A0,0.5,{ freq : 10 }); - specifying a frequency will force PWM output, even if the pin has a DAC
  • soft - boolean, If true software PWM is used if hardware is not available.
  • forceSoft - boolean, If true software PWM is used even if hardware PWM or a DAC is available

function Pin.read

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Call type:

function Pin.read()

Returns

Whether pin is a logical 1 or 0

Description

Returns the input state of the pin as a boolean.

Note: if you didn't call pinMode beforehand then this function will also reset the pin's state to "input"

function Pin.reset

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Call type:

function Pin.reset()

Description

Sets the output state of the pin to a 0

Note: if you didn't call pinMode beforehand then this function will also reset the pin's state to "output"

function Pin.set

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Call type:

function Pin.set()

Description

Sets the output state of the pin to a 1

Note: if you didn't call pinMode beforehand then this function will also reset the pin's state to "output"

function Pin.toggle

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Call type:

function Pin.toggle()

Returns

True if the pin is high after calling the function

Description

Toggles the state of the pin from off to on, or from on to off.

Note: This method doesn't currently work on the ESP8266 port of Espruino.

Note: if you didn't call pinMode beforehand then this function will also reset the pin's state to "output"

function Pin.write

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Call type:

function Pin.write(value)

Parameters

value - Whether to set output high (true/1) or low (false/0)

Description

Sets the output state of the pin to the parameter given

Note: if you didn't call pinMode beforehand then this function will also reset the pin's state to "output"

function Pin.writeAtTime

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Call type:

function Pin.writeAtTime(value, time)

Parameters

value - Whether to set output high (true/1) or low (false/0)

time - Time at which to write

Description

Sets the output state of the pin to the parameter given at the specified time.

Note:* this *doesn't change the mode of the pin to an output. To do that, you need to use pin.write(0) or pinMode(pin, 'output') first.

Note: This is not available in devices with low flash memory

process Class

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This class contains information about Espruino itself

Methods and Fields

process.env

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Call type:

process.env

Returns

An object

Description

Returns an Object containing various pre-defined variables.

  • VERSION - is the Espruino version
  • GIT_COMMIT - is Git commit hash this firmware was built from
  • BOARD - the board's ID (e.g. PUCKJS)
  • RAM - total amount of on-chip RAM in bytes
  • FLASH - total amount of on-chip flash memory in bytes
  • SPIFLASH - (on Bangle.js) total amount of off-chip flash memory in bytes
  • HWVERSION - For Puck.js this is the board revision (1, 2, 2.1), or for Bangle.js it's 1 or 2
  • STORAGE - memory in bytes dedicated to the Storage module
  • SERIAL - the serial number of this chip
  • CONSOLE - the name of the current console device being used (Serial1, USB, Bluetooth, etc)
  • MODULES - a list of built-in modules separated by commas
  • EXPTR - The address of the exportPtrs structure in flash (this includes links to built-in functions that compiled JS code needs)
  • APP_RAM_BASE - On nRF5x boards, this is the RAM required by the Softdevice if it doesn't exactly match what was allocated. You can use this to update LD_APP_RAM_BASE in the BOARD.py file

For example, to get a list of built-in modules, you can use process.env.MODULES.split(',')

Note: process.env is not writeable - so as not to waste RAM, the contents are generated on demand. If you need to be able to change them, use process.env=process.env; first to ensure the values stay allocated.

process.memory

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Call type:

process.memory(gc)

Parameters

gc - [optional] A boolean. If undefined or true Garbage collection is performed, if false it is not

Returns

Information about memory usage

Description

Run a Garbage Collection pass, and return an object containing information on memory usage.

  • free : Memory that is available to be used (in blocks)
  • usage : Memory that has been used (in blocks)
  • total : Total memory (in blocks)
  • history : Memory used for command history - that is freed if memory is low. Note that this is INCLUDED in the figure for 'free'
  • gc : Memory freed during the GC pass
  • gctime : Time taken for GC pass (in milliseconds)
  • blocksize : Size of a block (variable) in bytes
  • stackEndAddress : (on ARM) the address (that can be used with peek/poke/etc) of the END of the stack. The stack grows down, so unless you do a lot of recursion the bytes above this can be used.
  • stackFree : (on ARM) how many bytes of free execution stack are there at the point of execution.
  • flash_start : (on ARM) the address of the start of flash memory (usually 0x8000000)
  • flash_binary_end : (on ARM) the address in flash memory of the end of Espruino's firmware.
  • flash_code_start : (on ARM) the address in flash memory of pages that store any code that you save with save().
  • flash_length : (on ARM) the amount of flash memory this firmware was built for (in bytes). Note: Some STM32 chips actually have more memory than is advertised.

Memory units are specified in 'blocks', which are around 16 bytes each (depending on your device). The actual size is available in blocksize. See http://www.espruino.com/Performance for more information.

Note: To find free areas of flash memory, see require('Flash').getFree()

event process.uncaughtException

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Call type:

process.on('uncaughtException', function(exception) { ... });

Parameters

exception - The uncaught exception

Description

This event is called when an exception gets thrown and isn't caught (e.g. it gets all the way back to the event loop).

You can use this for logging potential problems that might occur during execution when you might not be able to see what is written to the console, for example:


var lastError;
process.on('uncaughtException', function(e) {
  lastError=e;
  print(e,e.stack?"\n"+e.stack:"")
});
function checkError() {
  if (!lastError) return print("No Error");
  print(lastError,lastError.stack?"\n"+lastError.stack:"")
}

Note: When this is used, exceptions will cease to be reported on the console - which may make debugging difficult!

process.version

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Call type:

process.version

Returns

The version of Espruino

Description

Returns the version of Espruino as a String

Promise Class

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This is the built-in class for ES6 Promises

Methods and Fields

Promise.all

View MDN documentation

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Call type:

Promise.all(promises)

Parameters

promises - An array of promises

Returns

A new Promise

Description

Return a new promise that is resolved when all promises in the supplied array are resolved.

Note: This is not available in devices with low flash memory

function Promise.catch

View MDN documentation

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Call type:

function Promise.catch(onRejected)

Parameters

onRejected - A callback that is called when this promise is rejected

Returns

The original Promise

constructor Promise

View MDN documentation

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Call type:

new Promise(executor)

Parameters

executor - A function of the form function (resolve, reject)

Returns

A Promise

Description

Create a new Promise. The executor function is executed immediately (before the constructor even returns) and

Note: This is not available in devices with low flash memory

Promise.reject

View MDN documentation

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Call type:

Promise.reject(promises)

Parameters

promises - Data to pass to the .catch handler

Returns

A new Promise

Description

Return a new promise that is already rejected (at idle it'll call .catch)

Note: This is not available in devices with low flash memory

Promise.resolve

View MDN documentation

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Call type:

Promise.resolve(promises)

Parameters

promises - Data to pass to the .then handler

Returns

A new Promise

Description

Return a new promise that is already resolved (at idle it'll call .then)

Note: This is not available in devices with low flash memory

function Promise.then

View MDN documentation

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Call type:

function Promise.then(onFulfilled, onRejected)

Parameters

onFulfilled - A callback that is called when this promise is resolved

onRejected - [optional] A callback that is called when this promise is rejected (or nothing)

Returns

The original Promise

ReferenceError Class

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The base class for reference errors - where a variable which doesn't exist has been accessed.

Methods and Fields

constructor ReferenceError

View MDN documentation

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Call type:

new ReferenceError(message)

Parameters

message - [optional] An message string

Returns

A ReferenceError object

Description

Creates a ReferenceError object

function ReferenceError.toString

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Call type:

function ReferenceError.toString()

Returns

A String

RegExp Class

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The built-in class for handling Regular Expressions

Note: Espruino's regular expression parser does not contain all the features present in a full ES6 JS engine. however some parts of the spec are not implemented:

There's a GitHub issue concerning RegExp features here

Methods and Fields

function RegExp.exec

View MDN documentation

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Call type:

function RegExp.exec(str)

Parameters

str - A string to match on

Returns

A result array, or null

Description

Test this regex on a string - returns a result array on success, or null otherwise.

/Wo/.exec("Hello World") will return:


[
 "Wo",
 "index": 6,
 "input": "Hello World"
]

Or with groups /W(o)rld/.exec("Hello World") returns:


[
 "World",
 "o", "index": 6,
 "input": "Hello World"
]

Note: This is not available in devices with low flash memory

constructor RegExp

View MDN documentation

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Call type:

new RegExp(regex, flags)

Parameters

regex - A regular expression as a string

flags - Flags for the regular expression as a string

Returns

A RegExp object

Description

Creates a RegExp object, for handling Regular Expressions

Note: This is not available in devices with low flash memory

function RegExp.test

View MDN documentation

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Call type:

function RegExp.test(str)

Parameters

str - A string to match on

Returns

true for a match, or false

Description

Test this regex on a string - returns true on a successful match, or false otherwise

Note: This is not available in devices with low flash memory

Serial Class

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This class allows use of the built-in USARTs

Methods may be called on the USB, Serial1, Serial2, Serial3, Serial4, Serial5 and Serial6 objects. While different processors provide different numbers of USARTs, on official Espruino boards you can always rely on at least Serial1 being available

Instances

Methods and Fields

function Serial.available

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Call type:

function Serial.available()

Returns

How many bytes are available

Description

Return how many bytes are available to read. If there is already a listener for data, this will always return 0.

event Serial.data

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Call type:

Serial.on('data', function(data) { ... });

Parameters

data - A string containing one or more characters of received data

Description

The data event is called when data is received. If a handler is defined with X.on('data', function(data) { ... }) then it will be called, otherwise data will be stored in an internal buffer, where it can be retrieved with X.read()

Serial.find

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Call type:

Serial.find(pin)

Parameters

pin - A pin to search with

Returns

An object of type Serial, or undefined if one couldn't be found.

Description

Try and find a USART (Serial) hardware device that will work on this pin (e.g. Serial1)

May return undefined if no device can be found.

function Serial.flush

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Call type:

function Serial.flush()

Description

Flush this serial stream (pause execution until all data has been sent)

Note: This is not available in devices with low flash memory

event Serial.framing

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Call type:

Serial.on('framing', function() { ... });

Description

The framing event is called when there was activity on the input to the UART but the STOP bit wasn't in the correct place. This is either because there was noise on the line, or the line has been pulled to 0 for a long period of time.

To enable this, you must initialise Serial with

SerialX.setup(..., { ...,
errors:true });

Note: Even though there was an error, the byte will still be received and passed to the data handler.

Note: This only works on STM32 and NRF52 based devices (e.g. all official Espruino boards)

function Serial.inject

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Call type:

function Serial.inject(data, ...)

Parameters

data, ... - One or more items to write. May be ints, strings, arrays, or special objects (see E.toUint8Array for more info).

Description

Add data to this device as if it came directly from the input - it will be returned via serial.on('data', ...);


Serial1.on('data', function(d) { print("Got",d); });
Serial1.inject('Hello World');
// prints "Got Hel","Got lo World" (characters can be split over multiple callbacks)

This is most useful if you wish to send characters to Espruino's REPL (console) while it is on another device.

Note: This is not available in devices with low flash memory

event Serial.parity

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Call type:

Serial.on('parity', function() { ... });

Description

The parity event is called when the UART was configured with a parity bit, and this doesn't match the bits that have actually been received.

To enable this, you must initialise Serial with

SerialX.setup(..., { ...,
errors:true });

Note: Even though there was an error, the byte will still be received and passed to the data handler.

Note: This only works on STM32 and NRF52 based devices (e.g. all official Espruino boards)

function Serial.pipe

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Call type:

function Serial.pipe(destination, options)

Parameters

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=32, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this USART to a stream (an object with a 'write' method)

Note: This is not available in devices with low flash memory

function Serial.print

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Call type:

function Serial.print(string)

Parameters

string - A String to print

Description

Print a string to the serial port - without a line feed

Note: This function replaces any occurrences of \n in the string with \r\n. To avoid this, use Serial.write.

function Serial.println

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Call type:

function Serial.println(string)

Parameters

string - A String to print

Description

Print a line to the serial port with a newline (\r\n) at the end of it.

Note: This function converts data to a string first, e.g. Serial.print([1,2,3]) is equivalent to

Serial.print("1,2,3"). If you'd like
 to write raw bytes, use
Serial.write`.

function Serial.read

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Call type:

function Serial.read(chars)

Parameters

chars - The number of characters to read, or undefined/0 for all available

Returns

A string containing the required bytes.

Description

Return a string containing characters that have been received

constructor Serial

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Call type:

new Serial()

Returns

A Serial object

Description

Create a software Serial port. This has limited functionality (only low baud rates), but it can work on any pins.

Use Serial.setup to configure this port.

function Serial.setConsole

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Call type:

function Serial.setConsole(force)

Parameters

force - Whether to force the console to this port

Description

Set this Serial port as the port for the JavaScript console (REPL).

Unless force is set to true, changes in the connection state of the board (for instance plugging in USB) will cause the console to change.

See E.setConsole for a more flexible version of this function.

function Serial.setup

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Call type:

function Serial.setup(baudrate, options)

Parameters

baudrate - The baud rate - the default is 9600

options - [optional] A structure containing extra information on initialising the serial port - see below.

Description

Setup this Serial port with the given baud rate and options.

e.g.


Serial1.setup(9600,{rx:a_pin, tx:a_pin});

The second argument can contain:


{
  rx:pin,                           // Receive pin (data in to Espruino)
  tx:pin,                           // Transmit pin (data out of Espruino)
  ck:pin,                           // (default none) Clock Pin
  cts:pin,                          // (default none) Clear to Send Pin
  bytesize:8,                       // (default 8)How many data bits - 7 or 8
  parity:null/'none'/'o'/'odd'/'e'/'even',
                                    // (default none) Parity bit
  stopbits:1,                       // (default 1) Number of stop bits to use
  flow:null/undefined/'none'/'xon', // (default none) software flow control
  path:null/undefined/string        // Linux Only - the path to the Serial device to use
  errors:false                      // (default false) whether to forward framing/parity errors
}

You can find out which pins to use by looking at your board's reference page and searching for pins with the UART/USART markers.

If not specified in options, the default pins are used for rx and tx (usually the lowest numbered pins on the lowest port that supports this peripheral). ck and cts are not used unless specified.

Note that even after changing the RX and TX pins, if you have called setup before then the previous RX and TX pins will still be connected to the Serial port as well - until you set them to something else using digitalWrite or pinMode.

Flow control can be xOn/xOff (flow:'xon') or hardware flow control (receive only) if cts is specified. If cts is set to a pin, the pin's value will be 0 when Espruino is ready for data and 1 when it isn't.

By default, framing or parity errors don't create framing or parity events on the Serial object because storing these errors uses up additional storage in the queue. If you're intending to receive a lot of malformed data then the queue might overflow E.getErrorFlags() would return FIFO_FULL. However if you need to respond to framing or parity errors then you'll need to use errors:true when initialising serial.

On Linux builds there is no default Serial device, so you must specify a path to a device - for instance: Serial1.setup(9600,{path:"/dev/ttyACM0"})

You can also set up 'software serial' using code like:


var s = new Serial();
s.setup(9600,{rx:a_pin, tx:a_pin});

However software serial doesn't use ck, cts, parity, flow or errors parts of the initialisation object.

function Serial.unsetup

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Call type:

function Serial.unsetup()

Description

If the serial (or software serial) device was set up, uninitialise it.

Note: This is not available in devices with low flash memory

function Serial.write

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Call type:

function Serial.write(data, ...)

Parameters

data, ... - One or more items to write. May be ints, strings, arrays, or special objects (see E.toUint8Array for more info).

Description

Write a character or array of data to the serial port

This method writes unmodified data, e.g. Serial.write([1,2,3]) is equivalent to Serial.write("\1\2\3"). If you'd like data converted to a string first, use Serial.print.

Server Class

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The socket server created by require('net').createServer

Methods and Fields

function Server.close

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Call type:

function Server.close()

Description

Stop listening for new connections

function Server.listen

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Call type:

function Server.listen(port)

Parameters

port - The port to listen on

Returns

The HTTP server instance that 'listen' was called on

Description

Start listening for new connections on the given port

Socket Class

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An actual socket connection - allowing transmit/receive of TCP data

Methods and Fields

function Socket.available

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Call type:

function Socket.available()

Returns

How many bytes are available

Description

Return how many bytes are available to read. If there is already a listener for data, this will always return 0.

event Socket.close

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Call type:

Socket.on('close', function(had_error) { ... });

Parameters

had_error - A boolean indicating whether the connection had an error (use an error event handler to get error details).

Description

Called when the connection closes.

event Socket.data

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Call type:

Socket.on('data', function(data) { ... });

Parameters

data - A string containing one or more characters of received data

Description

The 'data' event is called when data is received. If a handler is defined with X.on('data', function(data) { ... }) then it will be called, otherwise data will be stored in an internal buffer, where it can be retrieved with X.read()

event Socket.drain

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Call type:

Socket.on('drain', function() { ... });

Description

An event that is fired when the buffer is empty and it can accept more data to send.

function Socket.end

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Call type:

function Socket.end(data)

Parameters

data - A string containing data to send

Description

Close this socket - optional data to append as an argument.

See Socket.write for more information about the data argument

event Socket.error

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Call type:

Socket.on('error', function(details) { ... });

Parameters

details - An error object with an error code (a negative integer) and a message.

Description

There was an error on this socket and it is closing (or wasn't opened in the first place). If a "connected" event was issued on this socket then the error event is always followed by a close event. The error codes are:

  • -1: socket closed (this is not really an error and will not cause an error callback)
  • -2: out of memory (typically while allocating a buffer to hold data)
  • -3: timeout
  • -4: no route
  • -5: busy
  • -6: not found (DNS resolution)
  • -7: max sockets (... exceeded)
  • -8: unsent data (some data could not be sent)
  • -9: connection reset (or refused)
  • -10: unknown error
  • -11: no connection
  • -12: bad argument
  • -13: SSL handshake failed
  • -14: invalid SSL data

function Socket.pipe

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Call type:

function Socket.pipe(destination, options)

Parameters

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=32, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this to a stream (an object with a 'write' method)

Note: This is not available in devices with low flash memory

function Socket.read

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Call type:

function Socket.read(chars)

Parameters

chars - The number of characters to read, or undefined/0 for all available

Returns

A string containing the required bytes.

Description

Return a string containing characters that have been received

function Socket.write

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Call type:

function Socket.write(data)

Parameters

data - A string containing data to send

Returns

For node.js compatibility, returns the boolean false. When the send buffer is empty, a drain event will be sent

Description

This function writes the data argument as a string. Data that is passed in (including arrays) will be converted to a string with the normal JavaScript toString method.

If you wish to send binary data then you need to convert that data directly to a String. This can be done with String.fromCharCode, however it's often easier and faster to use the Espruino-specific E.toString, which will read its arguments as an array of bytes and convert that to a String:


socket.write(E.toString([0,1,2,3,4,5]));

If you need to send something other than bytes, you can use 'Typed Arrays', or even DataView:


var d = new DataView(new ArrayBuffer(8)); // 8 byte array buffer
d.setFloat32(0, 765.3532564); // write float at bytes 0-3
d.setInt8(4, 42); // write int8 at byte 4
socket.write(E.toString(d.buffer))

SPI Class

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This class allows use of the built-in SPI ports. Currently it is SPI master only.

Instances

  • SPI1 The first SPI port
  • SPI2 The second SPI port
  • SPI3 The third SPI port

Methods and Fields

SPI.find

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Call type:

SPI.find(pin)

Parameters

pin - A pin to search with

Returns

An object of type SPI, or undefined if one couldn't be found.

Description

Try and find an SPI hardware device that will work on this pin (e.g. SPI1)

May return undefined if no device can be found.

function SPI.send

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Call type:

function SPI.send(data, nss_pin)

Parameters

data - The data to send - either an Integer, Array, String, or Object of the form {data: ..., count:#}

nss_pin - An nSS pin - this will be lowered before SPI output and raised afterwards (optional). There will be a small delay between when this is lowered and when sending starts, and also between sending finishing and it being raised.

Returns

The data that was returned

Description

Send data down SPI, and return the result. Sending an integer will return an integer, a String will return a String, and anything else will return a Uint8Array.

Sending multiple bytes in one call to send is preferable as they can then be transmitted end to end. Using multiple calls to send() will result in significantly slower transmission speeds.

For maximum speeds, please pass either Strings or Typed Arrays as arguments. Note that you can even pass arrays of arrays, like [1,[2,3,4],5]

function SPI.send4bit

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Call type:

function SPI.send4bit(data, bit0, bit1, nss_pin)

Parameters

data - The data to send - either an integer, array, or string

bit0 - The 4 bits to send for a 0 (MSB first)

bit1 - The 4 bits to send for a 1 (MSB first)

nss_pin - An nSS pin - this will be lowered before SPI output and raised afterwards (optional). There will be a small delay between when this is lowered and when sending starts, and also between sending finishing and it being raised.

Description

Send data down SPI, using 4 bits for each 'real' bit (MSB first). This can be useful for faking one-wire style protocols

Sending multiple bytes in one call to send is preferable as they can then be transmitted end to end. Using multiple calls to send() will result in significantly slower transmission speeds.

function SPI.send8bit

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Call type:

function SPI.send8bit(data, bit0, bit1, nss_pin)

Parameters

data - The data to send - either an integer, array, or string

bit0 - The 8 bits to send for a 0 (MSB first)

bit1 - The 8 bits to send for a 1 (MSB first)

nss_pin - An nSS pin - this will be lowered before SPI output and raised afterwards (optional). There will be a small delay between when this is lowered and when sending starts, and also between sending finishing and it being raised

Description

Send data down SPI, using 8 bits for each 'real' bit (MSB first). This can be useful for faking one-wire style protocols

Sending multiple bytes in one call to send is preferable as they can then be transmitted end to end. Using multiple calls to send() will result in significantly slower transmission speeds.

Note: This is not available in devices with low flash memory

function SPI.setup

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Call type:

function SPI.setup(options)

Parameters

options - An Object containing extra information on initialising the SPI port

Description

Set up this SPI port as an SPI Master.

Options can contain the following (defaults are shown where relevant):


{
  sck:pin,
  miso:pin,
  mosi:pin,
  baud:integer=100000, // ignored on software SPI
  mode:integer=0, // between 0 and 3
  order:string='msb' // can be 'msb' or 'lsb'
  bits:8 // only available for software SPI
}

If sck,miso and mosi are left out, they will automatically be chosen. However if one or more is specified then the unspecified pins will not be set up.

You can find out which pins to use by looking at your board's reference page and searching for pins with the SPI marker. Some boards such as those based on nRF52 chips can have SPI on any pins, so don't have specific markings.

The SPI mode is between 0 and 3 - see http://en.wikipedia.org/wiki/SerialPeripheralInterfaceBus#Clockpolarityandphase

On STM32F1-based parts, you cannot mix AF and non-AF pins (SPI pins are usually grouped on the chip - and you can't mix pins from two groups). Espruino will not warn you about this.

constructor SPI

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Call type:

new SPI()

Returns

A SPI object

Description

Create a software SPI port. This has limited functionality (no baud rate), but it can work on any pins.

Use SPI.setup to configure this port.

function SPI.write

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Call type:

function SPI.write(data, ...)

Parameters

data, ... - One or more items to write. May be ints, strings, arrays, or special objects (see E.toUint8Array for more info).
If the last argument is a pin, it is taken to be the NSS pin

Description

Write a character or array of characters to SPI - without reading the result back.

For maximum speeds, please pass either Strings or Typed Arrays as arguments.

Storage Library

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This module allows you to read and write part of the nonvolatile flash memory of your device using a filesystem-like API.

Also see the Flash library, which provides a low level, more dangerous way to access all parts of your flash memory.

The Storage library provides two distinct types of file:

  • require("Storage").write(...)/require("Storage").read(...)/etc create simple contiguous files of fixed length. This is the recommended file type.
  • require("Storage").open(...) creates a StorageFile, which stores the file in numbered chunks ("filename\1"/"filename\2"/etc). It allows data to be appended and for the file to be read line by line.

You must read a file using the same method you used to write it - e.g. you can't create a file with require("Storage").open(...) and then read it with require("Storage").read(...).

Note: In firmware 2v05 and later, the maximum length for filenames is 28 characters. However in 2v04 and earlier the max length is 8.

Methods and Fields

Storage.compact

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Call type:

require("Storage").compact(showMessage)

Parameters

showMessage - [optional] If true, an overlay message will be displayed on the screen while compaction is happening. Default is false.

Description

The Flash Storage system is journaling. To make the most of the limited write cycles of Flash memory, Espruino marks deleted/replaced files as garbage/trash files and moves on to a fresh part of flash memory. Espruino only fully erases those files when it is running low on flash, or when compact is called.

compact may fail if there isn't enough RAM free on the stack to use as swap space, however in this case it will not lose data.

Note: compact rearranges the contents of memory. If code is referencing that memory (e.g. functions that have their code stored in flash) then they may become garbled when compaction happens. To avoid this, call eraseFiles before uploading data that you intend to reference to ensure that uploaded files are right at the start of flash and cannot be compacted further.

Note: This is not available in devices with low flash memory

Storage.erase

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Call type:

require("Storage").erase(name)

Parameters

name - The filename - max 28 characters (case sensitive)

Description

Erase a single file from the flash storage area.

Note: This function should be used with normal files, and not StorageFiles created with require("Storage").open(filename, ...). To erase those, use require("Storage").open(..., "r").erase().

Storage.eraseAll

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Call type:

require("Storage").eraseAll()

Description

Erase the flash storage area. This will remove all files created with require("Storage").write(...) as well as any code saved with save() or E.setBootCode().

Storage.getFree

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Call type:

require("Storage").getFree(checkInternalFlash)

Parameters

checkInternalFlash - Check the internal flash (rather than external SPI flash). Default false, so will check external storage

Returns

The amount of free bytes

Description

Return the amount of free bytes available in Storage. Due to fragmentation there may be more bytes available, but this represents the maximum size of file that can be written.

NOTE: checkInternalFlash is only useful on DICKENS devices - other devices don't use two different flash banks

Note: This is not available in devices with low flash memory

Storage.getStats

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Call type:

require("Storage").getStats(checkInternalFlash)

Parameters

checkInternalFlash - Check the internal flash (rather than external SPI flash). Default false, so will check external storage

Returns

An object containing info about the current Storage system

Description

Returns:


{
  totalBytes // Amount of bytes in filesystem
  freeBytes // How many bytes are left at the end of storage?
  fileBytes // How many bytes of allocated files do we have?
  fileCount // How many allocated files do we have?
  trashBytes // How many bytes of trash files do we have?
  trashCount // How many trash files do we have? (can be cleared with .compact)
}

NOTE: checkInternalFlash is only useful on DICKENS devices - other devices don't use two different flash banks

Note: This is not available in devices with low flash memory

Storage.hash

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Call type:

require("Storage").hash(regex)

Parameters

regex - [optional] If supplied, filenames are checked against this regular expression (with String.match(regexp)) to see if they match before being hashed

Returns

A hash of the files matching

Description

List all files in the flash storage area matching the specified regex (ignores StorageFiles), and then hash their filenames and file locations.

Identical files may have different hashes (e.g. if Storage is compacted and the file moves) but the chances of different files having the same hash are extremely small.


// Hash files
require("Storage").hash()
// Files ending in '.boot.js'
require("Storage").hash(/\.boot\.js$/)

Note: This function is used by Bangle.js as a way to cache files. For instance the bootloader will add all .boot.js files together into a single .boot0 file, but it needs to know quickly whether anything has changed.

Note: This is not available in devices with low flash memory

Storage.list

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Call type:

require("Storage").list(regex, filter)

Parameters

regex - [optional] If supplied, filenames are checked against this regular expression (with String.match(regexp)) to see if they match before being returned

filter - [optional] If supplied, File Types are filtered based on this: {sf:true} or {sf:false} for whether to show StorageFile

Returns

An array of filenames

Description

List all files in the flash storage area. An array of Strings is returned.

By default this lists files created by StorageFile (require("Storage").open) which have a file number ("\1"/"\2"/etc) appended to them.


// All files
require("Storage").list()
// Files ending in '.js'
require("Storage").list(/\.js$/)
// All Storage Files
require("Storage").list(undefined, {sf:true})
// All normal files (e.g. created with Storage.write)
require("Storage").list(undefined, {sf:false})

Note: This will output system files (e.g. saved code) as well as files that you may have written.

Storage.open

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Call type:

require("Storage").open(name, mode)

Parameters

name - The filename - max 27 characters (case sensitive)

mode - The open mode - must be either 'r' for read,'w' for write , or 'a' for append

Returns

An object containing {read,write,erase}

Description

Open a file in the Storage area. This can be used for appending data (normal read/write operations only write the entire file).

Please see StorageFile for more information (and examples).

Note: These files write through immediately - they do not need closing.

Note: This is not available in devices with low flash memory

Storage.optimise

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Call type:

require("Storage").optimise()

Description

Writes a lookup table for files into Bangle.js's storage. This allows any file stored up to that point to be accessed quickly.

Note: This is not available in devices with low flash memory

Storage.read

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Call type:

require("Storage").read(name, offset, length)

Parameters

name - The filename - max 28 characters (case sensitive)

offset - [optional] The offset in bytes to start from

length - [optional] The length to read in bytes (if <=0, the entire file is read)

Returns

A string of data, or undefined if the file is not found

Description

Read a file from the flash storage area that has been written with require("Storage").write(...).

This function returns a memory-mapped String that points to the actual memory area in read-only memory, so it won't use up RAM.

As such you can check if a file exists efficiently using require("Storage").read(filename)!==undefined.

If you evaluate this string with eval, any functions contained in the String will keep their code stored in flash memory.

Note: This function should be used with normal files, and not StorageFiles created with require("Storage").open(filename, ...)

Storage.readArrayBuffer

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Call type:

require("Storage").readArrayBuffer(name)

Parameters

name - The filename - max 28 characters (case sensitive)

Returns

An ArrayBuffer containing data from the file, or undefined

Description

Read a file from the flash storage area that has been written with require("Storage").write(...), and return the raw binary data as an ArrayBuffer.

This can be used:

  • In a DataView with new DataView(require("Storage").readArrayBuffer("x"))
  • In a Uint8Array/Float32Array/etc with
    new
    Uint8Array(require("Storage").readArrayBuffer("x"))

Note: This function should be used with normal files, and not StorageFiles created with require("Storage").open(filename, ...)

Note: This is not available in devices with low flash memory

Storage.readJSON

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Call type:

require("Storage").readJSON(name, noExceptions)

Parameters

name - The filename - max 28 characters (case sensitive)

noExceptions - If true and the JSON is not valid, just return undefined - otherwise an Exception is thrown

Returns

An object containing parsed JSON from the file, or undefined

Description

Read a file from the flash storage area that has been written with require("Storage").write(...), and parse JSON in it into a JavaScript object.

This is identical to JSON.parse(require("Storage").read(...)). It will throw an exception if the data in the file is not valid JSON.

Note: This function should be used with normal files, and not StorageFiles created with require("Storage").open(filename, ...)

Note: This is not available in devices with low flash memory

Storage.write

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Call type:

require("Storage").write(name, data, offset, size)

Parameters

name - The filename - max 28 characters (case sensitive)

data - The data to write

offset - [optional] The offset within the file to write (if 0/undefined a new file is created, otherwise Espruino attempts to write within an existing file if one exists)

size - [optional] The size of the file (if a file is to be created that is bigger than the data)

Returns

True on success, false on failure

Description

Write/create a file in the flash storage area. This is nonvolatile and will not disappear when the device resets or power is lost.

Simply write require("Storage").write("MyFile", "Some data") to write a new file, and require("Storage").read("MyFile") to read it.

If you supply:

  • A String, it will be written as-is
  • An array, will be written as a byte array (but read back as a String)
  • An object, it will automatically be converted to a JSON string before being written.

Note: If an array is supplied it will not be converted to JSON. To be explicit about the conversion you can use Storage.writeJSON

You may also create a file and then populate data later as long as you don't try and overwrite data that already exists. For instance:


var f = require("Storage");
f.write("a","Hello",0,14); // Creates a new file, 14 chars long
print(JSON.stringify(f.read("a"))); // read the file
// any nonwritten chars will be char code 255:
"Hello\u00FF\u00FF\u00FF\u00FF\u00FF\u00FF\u00FF\u00FF\u00FF"
f.write("a"," ",5); // write within the file
f.write("a","World!!!",6); // write again within the file
print(f.read("a")); // "Hello World!!!"
f.write("a"," ",0); // Writing to location 0 again will cause the file to be re-written
print(f.read("a")); // " "

This can be useful if you've got more data to write than you have RAM available - for instance the Web IDE uses this method to write large files into onboard storage.

Note: This function should be used with normal files, and not StorageFiles created with require("Storage").open(filename, ...)

Storage.writeJSON

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Call type:

require("Storage").writeJSON(name, data)

Parameters

name - The filename - max 28 characters (case sensitive)

data - The JSON data to write

Returns

True on success, false on failure

Description

Write/create a file in the flash storage area. This is nonvolatile and will not disappear when the device resets or power is lost.

Simply write require("Storage").writeJSON("MyFile", [1,2,3]) to write a new file, and require("Storage").readJSON("MyFile") to read it.

This is (almost) equivalent to require("Storage").write(name, JSON.stringify(data)) (see the notes below)

Note: This function should be used with normal files, and not StorageFiles created with require("Storage").open(filename, ...)

Note: Normally JSON.stringify converts any non-standard character to an escape code with \uXXXX, but as of Espruino 2v20, when writing to a file we use the most compact form, like \xXX or \X, as well as skipping quotes on fields. This saves space and is faster, but also means that if a String wasn't a UTF8 string but contained characters in the UTF8 codepoint range, when saved it won't end up getting reloaded as a UTF8 string. It does mean that you cannot parse the file with just JSON.parse as it's no longer standard JSON but is JS, so you must use Storage.readJSON

Note: This is not available in devices with low flash memory

StorageFile Class

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These objects are created from require("Storage").open and allow Storage items to be read/written.

The Storage library writes into Flash memory (which can only be erased in chunks), and unlike a normal filesystem it allocates files in one long contiguous area to allow them to be accessed easily from Espruino.

This presents a challenge for StorageFile which allows you to append to a file, so instead StorageFile stores files in chunks. It uses the last character of the filename to denote the chunk number (e.g. "foobar\1", "foobar\2", etc).

This means that while StorageFile files exist in the same area as those from Storage, they should be read using Storage.open (and not Storage.read).


f = require("Storage").open("foobar","w");
f.write("Hell");
f.write("o World\n");
f.write("Hello\n");
f.write("World 2\n");
f.write("Hello World 3\n");
// there's no need to call 'close'
// then
f = require("Storage").open("foobar","r");
f.read(13) // "Hello World\nH"
f.read(13) // "ello\nWorld 2\n"
f.read(13) // "Hello World 3"
f.read(13) // "\n"
f.read(13) // undefined
// or
f = require("Storage").open("foobar","r");
f.readLine() // "Hello World\n"
f.readLine() // "Hello\n"
f.readLine() // "World 2\n"
f.readLine() // "Hello World 3\n"
f.readLine() // undefined
// now get rid of file
f.erase();

Note: StorageFile uses the fact that all bits of erased flash memory are 1 to detect the end of a file. As such you should not write character code 255 ("\xFF") to these files.

Methods and Fields

function StorageFile.erase

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Call type:

function StorageFile.erase()

Description

Erase this StorageFile - after being called this file can no longer be written to.

Note: You shouldn't call require("Storage").erase(...) on a StorageFile, but should instead open the StorageFile and call .erase on the returned file: require("Storage").open(..., "r").erase()

Note: This is not available in devices with low flash memory

function StorageFile.getLength

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Call type:

function StorageFile.getLength()

Returns

The current length in bytes of the file

Description

Return the length of the current file.

This requires Espruino to read the file from scratch, which is not a fast operation.

Note: This is not available in devices with low flash memory

function StorageFile.pipe

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Call type:

function StorageFile.pipe(destination, options)

Parameters

destination - The destination file/stream that will receive content from the source.

options - [optional] An object { chunkSize : int=32, end : bool=true, complete : function }
chunkSize : The amount of data to pipe from source to destination at a time
complete : a function to call when the pipe activity is complete
end : call the 'end' function on the destination when the source is finished

Description

Pipe this file to a stream (an object with a 'write' method)

Note: This is not available in devices with low flash memory

function StorageFile.read

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Call type:

function StorageFile.read(len)

Parameters

len - How many bytes to read

Returns

A String, or undefined

Description

Read 'len' bytes of data from the file, and return a String containing those bytes.

If the end of the file is reached, the String may be smaller than the amount of bytes requested, or if the file is already at the end, undefined is returned.

Note: This is not available in devices with low flash memory

function StorageFile.readLine

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Call type:

function StorageFile.readLine()

Returns

A line of data

Description

Read a line of data from the file (up to and including "\n")

Note: This is not available in devices with low flash memory

function StorageFile.write

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Call type:

function StorageFile.write(data)

Parameters

data - The data to write. This should not include '\xFF' (character code 255)

Description

Append the given data to a file. You should not attempt to append "\xFF" (character code 255).

Note: This is not available in devices with low flash memory

String Class

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This is the built-in class for Text Strings.

Text Strings in Espruino are not zero-terminated, so you can store zeros in them.

Methods and Fields

function String.charAt

View MDN documentation

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Call type:

function String.charAt(pos)

Parameters

pos - The character number in the string. Negative values return characters from end of string (-1 = last char)

Returns

The character in the string

Description

Return a single character at the given position in the String.

function String.charCodeAt

View MDN documentation

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Call type:

function String.charCodeAt(pos)

Parameters

pos - The character number in the string. Negative values return characters from end of string (-1 = last char)

Returns

The integer value of a character in the string, or NaN if out of bounds

Description

Return the integer value of a single character at the given position in the String.

function String.concat

View MDN documentation

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Call type:

function String.concat(args, ...)

Parameters

args, ... - Strings to append

Returns

The result of appending all arguments to this string

Description

Append all arguments to this String and return the result. Does not modify the original String.

Note: This is not available in devices with low flash memory

function String.endsWith

View MDN documentation

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Call type:

function String.endsWith(searchString, length)

Parameters

searchString - The string to search for

length - [optional] The 'end' of the string - if left off the actual length of the string is used

Returns

true if the given characters are found at the end of the string, otherwise, false.

String.fromCharCode

View MDN documentation

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Call type:

String.fromCharCode(code, ...)

Parameters

code, ... - One or more character codes to create a string from (range 0-255).

Returns

The character

Description

Return the character(s) represented by the given character code(s).

function String.includes

View MDN documentation

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Call type:

function String.includes(substring, fromIndex)

Parameters

substring - The string to search for

fromIndex - [optional] The start character index (or 0 if not defined)

Returns

true if the given characters are in the string, otherwise, false.

function String.indexOf

View MDN documentation

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Call type:

function String.indexOf(substring, fromIndex)

Parameters

substring - The string to search for

fromIndex - [optional] Index to search from

Returns

The index of the string, or -1 if not found

Description

Return the index of substring in this string, or -1 if not found

function String.lastIndexOf

View MDN documentation

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Call type:

function String.lastIndexOf(substring, fromIndex)

Parameters

substring - The string to search for

fromIndex - [optional] Index to search from

Returns

The index of the string, or -1 if not found

Description

Return the last index of substring in this string, or -1 if not found

property String.length

View MDN documentation

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Call type:

property String.length

Returns

The value of the string

Description

Find the length of the string

function String.match

View MDN documentation

(top)

Call type:

function String.match(substr)

Parameters

substr - Substring or RegExp to match

Returns

A match array or null (see below):

Description

Matches an occurrence subStr in the string.

Returns null if no match, or:


"abcdef".match("b") == [
  "b",         // array index 0 - the matched string
  index: 1,    // the start index of the match
  input: "b"   // the input string
 ]
"abcdefabcdef".match(/bcd/) == [
  "bcd", index: 1,
  input: "abcdefabcdef"
 ]

'Global' RegExp matches just return an array of matches (with no indices):


"abcdefabcdef".match(/bcd/g) = [
  "bcd",
  "bcd"
 ]

function String.padEnd

View MDN documentation

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Call type:

function String.padEnd(targetLength, padString)

Parameters

targetLength - The length to pad this string to

padString - [optional] The string to pad with, default is ' '

Returns

A string containing this string padded to the correct length

Description

Pad this string at the end to the required number of characters


"Hello".padEnd(10) == "Hello     "
"123".padEnd(10,".-") == "123.-.-.-."

Note: This is not available in devices with low flash memory

function String.padStart

View MDN documentation

(top)

Call type:

function String.padStart(targetLength, padString)

Parameters

targetLength - The length to pad this string to

padString - [optional] The string to pad with, default is ' '

Returns

A string containing this string padded to the correct length

Description

Pad this string at the beginning to the required number of characters


"Hello".padStart(10) == "     Hello"
"123".padStart(10,".-") == ".-.-.-.123"

Note: This is not available in devices with low flash memory

function String.removeAccents

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Call type:

function String.removeAccents()

Returns

This string with the accents/diacritics (such as é, ü) removed from characters in the ISO 8859-1 set

Description

This is not a standard JavaScript function, but is provided to allow use of fonts that only support ASCII (char codes 0..127, like the 4x6 font) with character input that might be in the ISO8859-1 range.

Note: This is not available in devices with low flash memory

function String.repeat

View MDN documentation

(top)

Call type:

function String.repeat(count)

Parameters

count - An integer with the amount of times to repeat this String

Returns

A string containing repetitions of this string

Description

Repeat this string the given number of times.

Note: This is not available in devices with low flash memory

function String.replace

View MDN documentation

(top)

Call type:

function String.replace(subStr, newSubStr)

Parameters

subStr - The string (or Regular Expression) to search for

newSubStr - The string to replace it with. Replacer functions are supported, but only when subStr is a RegExp

Returns

This string with subStr replaced

Description

Search and replace ONE occurrence of subStr with newSubStr and return the result. This doesn't alter the original string.

function String.replaceAll

View MDN documentation

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Call type:

function String.replaceAll(subStr, newSubStr)

Parameters

subStr - The string (or Regular Expression) to search for

newSubStr - The string to replace it with. Replacer functions are supported, but only when subStr is a RegExp

Returns

This string with subStr replaced

Description

Search and replace ALL occurrences of subStr with newSubStr and return the result. This doesn't alter the original string.

function String.slice

View MDN documentation

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Call type:

function String.slice(start, end)

Parameters

start - The start character index, if negative it is from the end of the string

end - [optional] The end character index, if negative it is from the end of the string, and if omitted it is the end of the string

Returns

Part of this string from start for len characters

function String.split

View MDN documentation

(top)

Call type:

function String.split(separator)

Parameters

separator - The separator String or RegExp to use

Returns

Part of this string from start for len characters

Description

Return an array made by splitting this string up by the separator. e.g. '1,2,3'.split(',')==['1', '2', '3']

Regular Expressions can also be used to split strings, e.g.

'1a2b3
4'.split(/[^0-9]/)==['1', '2', '3', '4']
.

function String.startsWith

View MDN documentation

(top)

Call type:

function String.startsWith(searchString, position)

Parameters

searchString - The string to search for

position - [optional] The start character index (or 0 if not defined)

Returns

true if the given characters are found at the beginning of the string, otherwise, false.

constructor String

View MDN documentation

(top)

Call type:

new String(str, ...)

Parameters

str, ... - A value to turn into a string. If undefined or not supplied, an empty String is created.

Returns

A String

Description

Create a new String

function String.substr

View MDN documentation

(top)

Call type:

function String.substr(start, len)

Parameters

start - The start character index

len - [optional] The number of characters

Returns

Part of this string from start for len characters

function String.substring

View MDN documentation

(top)

Call type:

function String.substring(start, end)

Parameters

start - The start character index (inclusive)

end - [optional] The end character index (exclusive)

Returns

The part of this string between start and end

function String.toLowerCase

View MDN documentation

(top)

Call type:

function String.toLowerCase()

Parameters

Returns

The lowercase version of this string

function String.toUpperCase

View MDN documentation

(top)

Call type:

function String.toUpperCase()

Parameters

Returns

The uppercase version of this string

function String.trim

View MDN documentation

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Call type:

function String.trim()

Returns

A String with Whitespace removed from the beginning and end

Description

Return a new string with any whitespace (tabs, space, form feed, newline, carriage return, etc) removed from the beginning and end.

SyntaxError Class

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The base class for syntax errors

Methods and Fields

constructor SyntaxError

View MDN documentation

(top)

Call type:

new SyntaxError(message)

Parameters

message - [optional] An message string

Returns

A SyntaxError object

Description

Creates a SyntaxError object

function SyntaxError.toString

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Call type:

function SyntaxError.toString()

Returns

A String

tls Library

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This library allows you to create TCPIP servers and clients using TLS encryption

In order to use this, you will need an extra module to get network connectivity.

This is designed to be a cut-down version of the node.js library. Please see the Internet page for more information on how to use it.

Methods and Fields

tls.connect

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Call type:

require("tls").connect(options, callback)

Parameters

options - An object containing host,port fields

callback - A function(res) that will be called when a connection is made. You can then call res.on('data', function(data) { ... }) and res.on('close', function() { ... }) to deal with the response.

Returns

Returns a new net.Socket object

Description

Create a socket connection using TLS

Options can have ca, key and cert fields, which should be the decoded content of the certificate.


var options = url.parse("localhost:1234");
options.key = atob("MIIJKQ ... OZs08C");
options.cert = atob("MIIFi ... Uf93rN+");
options.ca = atob("MIIFgDCC ... GosQML4sc=");
require("tls").connect(options, ... );

If you have the certificates as .pem files, you need to load these files, take the information between the lines beginning with ----, remove the newlines from it so you have raw base64, and then feed it into atob as above.

You can also: * Just specify the filename (<=100 characters) and it will be loaded and parsed if you have an SD card connected. For instance options.key = "key.pem"; * Specify a function, which will be called to retrieve the data. For instance `options.key = function() { eeprom.loadmyinfo(); };

For more information about generating and using certificates, see:

https://engineering.circle.com/https-authorized-certs-with-node-js/

(You'll need to use 2048 bit certificates as opposed to 4096 bit shown above)

Note: This is only available in devices with TLS and SSL support (Espruino Pico and Espruino WiFi only)

tv Library

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This library provides TV out capability on the Espruino and Espruino Pico.

See the Television page for more information.

Methods and Fields

tv.setup

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Call type:

require("tv").setup(options, width)

Parameters

options - Various options for the TV output

width -

Returns

A graphics object

Description

This initialises the TV output. Options for PAL are as follows:


var g = require('tv').setup({ type : "pal",
  video : A7, // Pin - SPI MOSI Pin for Video output (MUST BE SPI1)
  sync : A6, // Pin - Timer pin to use for video sync
  width : 384,
  height : 270, // max 270
});

and for VGA:


var g = require('tv').setup({ type : "vga",
  video : A7, // Pin - SPI MOSI Pin for Video output (MUST BE SPI1)
  hsync : A6, // Pin - Timer pin to use for video sync
  vsync : A5, // Pin - pin to use for video sync
  width : 220,
  height : 240,
  repeat : 2, // amount of times to repeat each line
});

or


var g = require('tv').setup({ type : "vga",
  video : A7, // Pin - SPI MOSI Pin for Video output (MUST BE SPI1)
  hsync : A6, // Pin - Timer pin to use for video sync
  vsync : A5, // Pin - pin to use for video sync
  width : 220,
  height : 480,
  repeat : 1, // amount of times to repeat each line
});

See the Television page for more information.

TypeError Class

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The base class for type errors

Methods and Fields

function TypeError.toString

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Call type:

function TypeError.toString()

Returns

A String

constructor TypeError

View MDN documentation

(top)

Call type:

new TypeError(message)

Parameters

message - [optional] An message string

Returns

A TypeError object

Description

Creates a TypeError object

Uint16Array Class

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This is the built-in JavaScript class for a typed array of 16 bit unsigned integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Uint16Array

View MDN documentation

(top)

Call type:

new Uint16Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Uint24Array Class

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This is the built-in JavaScript class for a typed array of 24 bit unsigned integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Uint24Array

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Call type:

new Uint24Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Note: This is not available in devices with low flash memory

Uint32Array Class

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This is the built-in JavaScript class for a typed array of 32 bit unsigned integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Uint32Array

View MDN documentation

(top)

Call type:

new Uint32Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Uint8Array Class

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This is the built-in JavaScript class for a typed array of 8 bit unsigned integers.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Uint8Array

View MDN documentation

(top)

Call type:

new Uint8Array(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Uint8ClampedArray Class

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This is the built-in JavaScript class for a typed array of 8 bit unsigned integers that are automatically clamped to the range 0 to 255.

Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).

Arrays of this type include all the methods from ArrayBufferView

Methods and Fields

constructor Uint8ClampedArray

View MDN documentation

(top)

Call type:

new Uint8ClampedArray(arr, byteOffset, length)

Parameters

arr - The array or typed array to base this off, or an integer which is the array length

byteOffset - The byte offset in the ArrayBuffer (ONLY IF the first argument was an ArrayBuffer)

length - The length (ONLY IF the first argument was an ArrayBuffer)

Returns

A typed array

Description

Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBufferView (e.g. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.

Clamped arrays clamp their values to the allowed range, rather than 'wrapping'. e.g. after a[0]=12345;, a[0]==255.

url Class

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This class helps to convert URLs into Objects of information ready for http.request/get

Methods and Fields

url.parse

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Call type:

url.parse(urlStr, parseQuery)

Parameters

urlStr - A URL to be parsed

parseQuery - Whether to parse the query string into an object not (default = false)

Returns

An object containing options for http.request or http.get. Contains method, host, path, pathname, search, port and query

Description

A utility function to split a URL into parts

This is useful in web servers for instance when handling a request.

For instance url.parse("/a?b=c&d=e",true) returns {"method":"GET","host":"","path":"/a?b=c&d=e","pathname":"/a","search":"?b=c&d=e","port":80,"query":{"b":"c","d":"e"}}

Waveform Class

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This class handles waveforms. In Espruino, a Waveform is a set of data that you want to input or output.

Methods and Fields

function Waveform.startInput

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Call type:

function Waveform.startInput(output, freq, options)

Parameters

output - The pin to output on

freq - The frequency to output each sample at

options - Optional options struct {time:float,repeat:bool} where: time is the that the waveform with start output at, e.g. getTime()+1 (otherwise it is immediate), repeat is a boolean specifying whether to repeat the give sample

Description

Will start inputting the waveform on the given pin that supports analog. If not repeating, it'll emit a finish event when it is done.

Note: This is not available in devices with low flash memory

function Waveform.startOutput

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Call type:

function Waveform.startOutput(output, freq, options)

Parameters

output - The pin to output on

freq - The frequency to output each sample at

options - Optional options struct {time:float,repeat:bool} where: time is the that the waveform with start output at, e.g. getTime()+1 (otherwise it is immediate), repeat is a boolean specifying whether to repeat the give sample

Description

Will start outputting the waveform on the given pin - the pin must have previously been initialised with analogWrite. If not repeating, it'll emit a finish event when it is done.

Note: This is not available in devices with low flash memory

function Waveform.stop

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Call type:

function Waveform.stop()

Description

Stop a waveform that is currently outputting

Note: This is not available in devices with low flash memory

constructor Waveform

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Call type:

new Waveform(samples, options)

Parameters

samples - The number of samples

options - Optional options struct {doubleBuffer:bool, bits : 8/16} where: doubleBuffer is whether to allocate two buffers or not (default false), and bits is the amount of bits to use (default 8).

Returns

An Waveform object

Description

Create a waveform class. This allows high speed input and output of waveforms. It has an internal variable called buffer (as well as buffer2 when double-buffered - see options below) which contains the data to input/output.

When double-buffered, a 'buffer' event will be emitted each time a buffer is finished with (the argument is that buffer). When the recording stops, a 'finish' event will be emitted (with the first argument as the buffer).

Note: This is not available in devices with low flash memory

WIZnet Library

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Library for communication with the WIZnet Ethernet module

Methods and Fields

WIZnet.connect

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Call type:

require("WIZnet").connect(spi, cs)

Parameters

spi - Device to use for SPI (or undefined to use the default)

cs - The pin to use for Chip Select

Returns

An Ethernet Object

Description

Initialise the WIZnet module and return an Ethernet object

Note: This is only available in builds with support for WIZnet Ethernet modules built in