Feature: synchronous mode for text processing

[lojjic]

Running async in a web worker is a huge win for perceived performance, but there may be cases where running synchronously in the main thread would be preferable. Since worker modules can already fall back to execution in the main thread, we could add some sort of flag to force that.

[lojjic]

Thinking about this more closely, just moving to main thread wouldn't make this synchronous on its own; other things such as font loading would have to be made synchronous and the text processing interfaces adjusted as well.

[peterqliu]

I have a workflow that involves multiple worker passes to download data and generate the objects to visualize them. In this context, I'd like the workers to be as versatile as possible. can we bundle the "caller code" and "worker code" in a way that users can run it on specified threads?

To illustrate, I would use that to

• Invoke new Text() from a worker thread
• specify an existing worker to do the text-processing work, with a callback to pass the result to the main thread

(Edit: just realized this isn't really about sync mode, but hopefully the threading theme is relevant enough)