Web Worker and Shared Worker for Dart

This package provides 2 things.

1. Dart wrappers for Web Worker and SharedWorker. One that talks to the Worker, and one that inside a Worker. All in the same project, written in Dart.
2. A solution to develop with dartdevc and webdev serve even when Web Worker will not start up correctly.

Some background about point number 2:

Web Worker is all along working well with webdev serve --release, or compiling it with dart2js. But having Web Worker code actively developing alongside the main application in the same project with dartdevc is not possible because Worker will not launch correctly with webdev serve.

This is likely a bug, or a feature yet to be supported. Before it is figured out by Dart, this package can bridge that gap, with a little bit of work.

Normal Web Worker Usage

These examples will only work if you use webdev serve --release.

Inside the Web Worker

import 'package:dorker/dorker.dart';

main() {
  var _boss = DorkerBoss();
  _boss.onMessage.listen((data_from_main) => print(data_from_main));
  _boss.postMessage.add('Yes Boss');
}

In the main application

import 'dart:html';

import 'package:dorker/dorker.dart';

void main() {
    _dorker = DorkerWorker(Worker('worker.dart.js'));
    _dorker.onMessage.listen((data_from_worker) => print(data_from_worker));
    _dorker.postMessage.add('Start working!');
}

Develop Web Worker powered project with dartdevc

The main idea is encapsulate the communication to/from Web Worker with Dorker. And then passing a special environment variable when we build with webdev serve --release. This can be done with a build.yaml, which is in this repro.

import 'dart:html';

import 'package:dorker/dorker.dart';

import 'lib/concater.dart';

void main() {
  Dorker _concatDorker;
  if (const String.fromEnvironment('USE_WORKER') == 'true') {
    print('Asked to use worker');
    _concatDorker = DorkerWorker(Worker('worker/concater_worker.dart.js'));
  } else
  {
    print('Not using worker');
    _concatDorker = Dorker();
    Concater(Dorker.CrossLink(_concatDorker));
  }
}

Example folder provided a good guideline of how to pull this off. You can the example by running either webdev serve or webdev serve -r.

A Note about SharedWorker

For all the example listed above, you can safely replace [DorkerWorker] with [DorkerSharedWorker], then [Worker] with [SharedWorker] and [DorkerBoss] with [DorkerSharedBoss].

Warning: SharedWorker will not work as intended in multiple tab for dcc built, aka webdev serve.

Just make sure you know why are you using Worker or SharedWorker, study them here: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API.

---

To follow my personal story of how I come to this, you can check out my post here.