flutter_js: ^0.0.2+1
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import 'package:flutter_js/flutter_js.dart';
void main() => runApp(MyApp());
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
String _jsResult = '';
int _idJsEngine = -1;
@override
void initState() {
super.initState();
initJsEngine();
}
// Platform messages are asynchronous, so we initialize in an async method.
Future<void> initJsEngine() async {
try {
_idJsEngine = await FlutterJs.initEngine();
} on PlatformException catch (e) {
print('Failed to init js engine: ${e.details}');
}
// If the widget was removed from the tree while the asynchronous platform
// message was in flight, we want to discard the reply rather than calling
// setState to update our non-existent appearance.
if (!mounted) return;
}
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('FlutterJS Example'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('JS Evaluate Result: $_jsResult\n'),
SizedBox(height: 20,),
Padding(padding: EdgeInsets.all(10), child: Text('Click on the big JS Yellow Button to evaluate the expression bellow using the flutter_js plugin'),),
Padding(
padding: const EdgeInsets.all(8.0),
child: Text("Math.trunc(Math.random() * 100).toString();", style: TextStyle(fontSize: 12, fontStyle: FontStyle.italic, fontWeight: FontWeight.bold),),
)
],
),
),
floatingActionButton: FloatingActionButton(
backgroundColor: Colors.transparent,
child: Image.asset('assets/js.ico'),
onPressed: () async {
try {
String result = await FlutterJs.evaluate(
"Math.trunc(Math.random() * 100).toString();", _idJsEngine);
setState(() {
_jsResult = result;
});
} on PlatformException catch (e) {
print('ERRO: ${e.details}');
}
},
),
),
);
}
}
Alternatives
There were another packages which provides alternatives to evaluate javascript in flutter projects:
https://pub.flutter-io.cn/packages/flutter_liquidcore
Good, is based on https://github.com/LiquidPlayer/LiquidCore
It is based on V8 engine so the exectuable library is huge (20Mb). So the final app will be huge too.
https://pub.flutter-io.cn/packages/interactive_webview
Allows to evaluate javascript in a hidden webview. Does not add weight to size of the app, but a webview means a entire browser is in memory just to evaluate javascript code. So we think an embeddable engine is a way better solution.
https://pub.flutter-io.cn/packages/jsengine
Based on jerryscript which is slower than quickjs. The jsengine package does not have implementation to iOS.