dart_quickjs #

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dart_quickjs is a binding for the QuickJS engine using Dart, which supports executing JavaScript code on Android and iOS. QuickJS is a lightweight JavaScript engine that supports the ECMAScript 2020 specification.

Get started #

Add dependency #

$ dart pub add dart_quickjs

If you need to specify a version, you can add it to the pubspec.yaml file.

dependencies:
  dart_quickjs: ^Version number

Latest stable version：

Example #

println is the print function injected by dart_quickjs.

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();
const script = 'println("Hello World");';

runtime.evaluateJavaScript(script, 'main.js');

Type support and mapping #

Injecting objects #

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();
// Creating and injecting objects
final value = JSString.create(runtime.context, 'dart_quickjs');
// Add to global objects
runtime.global.setPropertyStr('name', value);
// Print name
runtime.evaluateJavaScript('println(name);', 'main.js');

Injecting methods #

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();
// Creating methods
final value = JSFunction.create(runtime.context, (JSNumber data) {
  return JSNumber.create(runtime.context, data.value + 1);
});
// Add to global objects
runtime.global.setPropertyStr('add', value);
// Execute code
runtime.evaluateJavaScript('println(add(1));', 'main.js');

Communication #

Calling Dart from JavaScript

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();
// Creating methods
final value = JSFunction.create(runtime.context, (JSString message) {
  print('JavaScriptMessage: ${message.value}');
});
// Add to global objects
runtime.global.setPropertyStr('test', value);
// Execute code
runtime.evaluateJavaScript('test("dart_quickjs");', 'main.js');

Calling JavaScript from Dart

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();
// JavaScript code
const code  = '''function message(value) {
  return value + 1;
}
message;''';
// Execute code
final callback = runtime.evaluateJavaScript(code, 'main.js') as JSFunction;
// Calling JavaScript methods
final value = callback.call([JSNumber.create(runtime.context, 1)]);
// Print return value
print(value);

In communication, you can pass basic types and function types.

Module import #

• When using the module system, you need to pass the moduleLoader method to load modules.
• When running the entry point, the run mode needs to be set to JSEvalType.module.

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime(
  moduleLoader: (String name) {
    if (name == 'message') {
      return "export const message = 'dart_quickjs'";
    }

    return '';
  },
);
// main.js
const main  = '''
  import { message } from 'message'
  println(message)
''';
// Execute code
runtime.evaluateJavaScript(main, 'main.js', JSEvalType.module);

Plugin #

import 'package:dart_quickjs/dart_quickjs.dart';

class Test extends Plugin {
  late Runtime _runtime;

  @override
  void onCreate(Runtime runtime) {
    _runtime = runtime;
    // Injection Method
    runtime.global.setPropertyStr(
      'getMessage',
      JSFunction.create(runtime.context, test),
    );
  }

  JSString test(JSString data) {
    return JSString.create(_runtime.context, '${data.value} World');
  }

  @override
  void destroy(Runtime runtime) {}
}

final runtime = Runtime(
  plugins: [
    // Register Plugin
    Test()
  ],
);

const script = 'println(getMessage("Hello"));';
runtime.evaluateJavaScript(script, 'main.js');

Bytecode #

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();

const script = 'println("Hello World");';
// Compile Bytecode
final bytecode = runtime.compile(script, 'main.js');
// Run Bytecode
runtime.evaluateBytecode(bytecode);

Destroy and release #

import 'package:dart_quickjs/dart_quickjs.dart';

final runtime = Runtime();

runtime.destroy();

Built-in API methods #

println setInterval clearInterval setTimeout clearTimeout

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