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"Lightweight" JS interpreter for ESP32. Provides JS-based eventloop implementationand native asynchronous network and timer functions.Because of the limited memory on ESP32-WROOM modules, the full functionality is currently only realizable on ESP32-WROVER and ESP32-S2-WROVER modules, that came with at least 2MB integrated SPIRAM.

Getting started

API

Compatibility

Installesp-idf 4.2.2 on your system.

Clone esp32-javascript inside your esp directory (normally ~/esp):

cd~/esp    git clone https://github.com/pepe79/esp32-javascript.git

Change into ~/esp/esp32-javascript

cd~/esp/esp32-javascript

Maybe you want to change the BOARD_VARIANT in the ./CMakeLists.txt filefor the integrated arduino-esp32 bindings.

First build the project with

#for ESP32 devices    idf.py build#for ESP32-S2 devices    idf.py -DIDF_TARGET=esp32s2 build

Connect your ESP32 Dev Board via USB and run

    idf.py flash monitor

Use the keyboard shortcutAltGr + ] to leave serial monitor.

Now you have installed the pre-configured boot script.

If this is your first install, your onboard LED should blink now. Blinking signals that your board has started a soft ap with the ssid "esp32". With your mobile or desktop connect to the WLAN SSID "esp32" and openhttp://192.168.4.1/setup (if you have not changed the default credentials your username / password is esp32 / esp32 ). You can change the default password infirmware-config.ts by changing the value of keypassword.

On the Setup page you can configure your WLAN settings and an URL to download your JS main script from.

Please note that the Javascript OTA script, does not need to have a main function, because its evaluated entirely.That means, to print out "Hello World", you only have to include one line in your script on the webserver:

console.log("Hello world!");

You can test this example by configuring this URL as "Javascript OTA":https://raw.githubusercontent.com/marcelkottmann/esp32-javascript/master/examples/example.js

Please see also the other example in./examples

If you need to create your own C/C++ bindings for your JS code, this are the steps to perform:

1. Create a file namedproject.cpp in the./main directory
2. Implement the esp32_javascript_main callback function inside thisproject.ccp:

#include"esp32-javascript.h"externvoidesp32_javascript_main(duk_context*ctx)   {// do your own duktape bindings here   }

SeeDuktape Programmer's Guide for more information regarding Duktape bindings.

If you need more than this, you can create your own esp-idf component below./components. Then delegate theesp32_javascript_main function to this component.Additionally you have to set your component name in the top level./CMakeLists.txt. Refer to the documentation next to the settingESP32_JS_PROJECT_NAME.SeeESP Build System for information on how to create a component with the esp-idf build system.

You can perform a native firmware OTA upgrade by calling the URL /setup . There is a section called "Native OTA" where you can provide two urls to the new images: One for the actual firmware image (normally named esp32-javascript.bin in your build directory) and the other for the JS modules image (normally named modules.bin in your build directory).

The upgrade is performed in the background. You can check the upgrade status either by staying on the upgrade page, which is reloaded automatically every ~20 seconds or click on "Upgrade status" in the setup page.

After upgrade has finished you have to restart the device to load the new firmware.

You can clean the project by executing

    idf.py fullclean

If you want to use all the esp32-javascript defaults for your sdkconfig. Remove./sdkconfig file. This file will be recreated the next build with all the defaults.

You can erase the persistent flash memory, which will be equivalent to a factory reset, by executing

    idf.py erase_flash

• Supported chips ESP32 and ESP32-S2
• 2 MB Minimum Flash Size
• 2 MB Minimum external SPI RAM (WROVER)

¹ SSL client connections currently not working properly for ESP32-S2 devices due to esp-idf bug in 4.2.x:espressif/esp-idf#6998 , but can be fixed manually (see changes in PR).

Theexamples directory contains arepl that can be used as JS OTA Url:https://raw.githubusercontent.com/marcelkottmann/esp32-javascript/http-streaming/examples/repl.js

The repl can be used with netcat directly or with a combination of rlwrap and netcat to have a history-support:rlwrap netcat [IP-ADDRESS] 1234

Enter username and password separated with colon(:) to authenticate, e.g.esp32:esp32 + Enter

~/esp/esp32-javascript> rlwrap netcat 192.168.188.24 1234> esp32:esp32====> authorized.> console.log('Hello world.')LOG|Hello world.====> undefined>

API documentation

Update documentation by executing

    npm run doc

See source files.