This sample demonstrates running JavaScript applications in a sandbox inside a microcontroller. The sample uses the jerryscript library for Sming.

To save space and be able to run JerryScript on an embedded device Sming compiles this library without a parser. This means that the JavaScript files have to be compiled before landing on the device. This sample demonstrates how this is done automatically for you.


The initial JavaScript code used in this sample is located in files/main.js. The code has one global variable x and two functions setup and loop. As shown below:

var x;

 * This is a function that will be called once.
function setup() {
        x = 0;
        print ('Setup: X='+x);

 * This is a function that will be called every half a second
function loop() {
        print('Loop: X='+x);

Once compiled the source code will be converted into a byte-code that will be executed inside of your microcontroller. In JerryScript this final byte-code is called snapshot or just snap.


This sample will run first the setup JavaScript function and then execute in an endless loop the loop function.


SoC support

  • esp32

  • esp32c3

  • esp32s2

  • esp32s3

  • esp8266

  • host

  • rp2040