I was looking for a way to implement some kind of dynamic plug-in system in Dart. The idea was to load Dart code on demand into an isolate using spawnUri(). It turns out that this function is implemented in the Dart VM but neither in Dartium nor does it compile down to JavaScript.

Falling back to spawnFunction() works as expected in the browser but it turns out that isolates are not allowed to access / change the DOM. This reduces isolates to dumb worker functions. Plug-ins which make contributions to the UI are not possible using this approach.

I created some test scripts for the browser and the VM to test the possibilities you have with isolates. You can find them at GitHub: https://github.com/hpehl/dart-isolates. Let me know what you think.