Web Workers API Shim (on top of Google Gears)

Credits

Jonathan 'J5' Cook

Demo

Click the button below to demo this thing.

Information

A class/constructor implements the worker's internal state (WorkerGlobalScope) according to the WebWorker API

A worker class which instantiates the new worker thread and and the managing class (DedicatedWorker)

What's Not Done

Some stuff from the API is not yet implemented:

• Implementing the communication between Worker and WorkerGlobalScope via MessagePort objects...
• implementing SharedWorker (which requires MessagePorts and may or may not be possible ... we'll see)
• onerror handlers
• The internal list of Documents that the API says the Worker keeps. That part seriously doesn't make sense to me.
• The close() method of the worker which tells the WorkerGlobalScope to quit, etc.
• The database methods available to WebWorkers via HTML5

Lessons Learned

A few items I learned working on this code:

• Gears HttpRequest object does not support synchronous/blocking downloads. Solution is to prefetch what your worker needs and run the scripts as they are asked for, rather than ask, load and run.
• Gears JS environment is missing some methods from Array object ... shift() and splice() didn't work for me at all.
• Safari 4 native implementation of Worker doesn't support nested workers (inner/child workers)
• throw new Error(...) is the new alert(...)

A Peek at the Worker's Internal Code