Support isolate

[623637646]

My JS code is enormous computation. I have to call it on non-main isolate. But I can't do it cause of a crash: "Unhandled Exception: Exception: Null check operator used on a null value". The reason is spawned isolates do not have access to the root bundle flutter/flutter#61480 (comment)

This demo shows what I want.

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_js/flutter_js.dart';

void main() async {
  runApp(MaterialApp(
    home: Scaffold(
      body: Center(child: Text("hello word")),
    ),
  ));

  final jsCode = "2+3;";

  // This code has error: "Unhandled Exception: Exception: Null check operator used on a null value".
  final String result = await compute(_execute, jsCode);

  // This code works fine.
  // final int result = await _execute(jsCode);
  print(result);
}

Future<T> _execute<T>(String jsCode) async {
  final javascriptRuntime = getJavascriptRuntime();
  final result = javascriptRuntime.evaluate(jsCode);
  return javascriptRuntime.convertValue(result);
}

[wardy484]

This would be great, I have a process that does a lot of processing (unfortuantely in JS).

[jpolstre]

I had some problems with this package and on reviewing the code I found that it depends on Quickjs Dart, which apparently already performs the operations in a separate isolation.

[sirenoremac]

If you do not need xhr, you can pass false to the xhr parameter of getJavascriptRuntime() and it will not try to access the root bundle:
final javascriptRuntime = getJavascriptRuntime(xhr: false);

If you do this, it will work in an isolate.

[abner]

If you do not need xhr, you can pass false to the xhr parameter of getJavascriptRuntime() and it will not try to access the root bundle: final javascriptRuntime = getJavascriptRuntime(xhr: false);

If you do this, it will work in an isolate.

By now I think it is the best suitable solution. I would have to dig more and change the way we load the polyfills to xhr and fetch, so it doesn't rely in access rootBundle (put them fixed as strings into the code would be the solution)