QuickJS Dart

A dart binding for QuickJS, a modern Javascript interpreter written in C by Fabrice Bellard

We can run javascript VM embedded to DartVM, using Dart:FFI

ENV requirement

1. dart lang 2.8+
2. clang
3. llvm(optional)
4. ios 9+
5. android api 21+

Quick Start

// dart code

import 'package:quickjs_dart/quickjs_dart.dart';

void main(){

   JSEngine(); // initialize engine

   String jsString = r"""
      function testAdd(x,y){
         return x+y;
      }
      testAdd
   """
   var engine= JSEngine.instance; // singleton

   var testAdd = engine.evalScript(jsString);

   print(testAdd.isFunction()); // true
   
   var result= testAdd.callJS([engine.newInt32(12),engine.newInt32(34)]); // 2 params, 12 and 34;
   
   result.jsPrint(); // use `console.log` in javascript, 46 is the result;
}

Table of Content

1. QuickJS Dart
   1. ENV requirement
   2. Quick Start
   3. Table of Content
   4. Build and Run (local machine only)
   5. Why not V8/jscore, and why QuickJS
   6. Why not PlatformChannel/MethodChannel and why Dart:FFI
   7. Docs and APIs

Build and Run (local machine only)

1. build quickjs lib for ios/android/dartVM

   sh ~/.build_all.sh

   or build android only

   sh ~/.build_android.sh

   or bulid ios only

   sh ~/.build_ios.sh

2. run dart on dart vm

    dart main.dart

3. if you come up with file system relative paths not allowed in hardened programs with macos, run this

   codesign --remove-signature /usr/local/bin/dart

4. run flutter example, android or ios

   note: run flutter doctor -v to examine the flutter env is correctly

   Then you can run example app

   cd example && flutter run

Why not V8/jscore, and why QuickJS

V8 is too big for small app and IOT devices. jscore is a bit old and slow for modern app.

Quickjs follows latest Javascript standard (ES2020) now. And it is fast enough, see benchmark

Why not PlatformChannel/MethodChannel and why Dart:FFI

PlatformChannel/MethodChannel(s) are designed for communication, post and receive data, and use features that had been made by exisiting Android/iOS/Native modules. It's not managed by Dart/Flutter itself.

Using Dart:FFI, we get possibilities to expand the dart/flutter. We can call native function, back and forward, adding Callbacks, manage memory of functions and values.

Docs and APIs

Do it later