Add customWorkerFactory to customize tsworker directly

[x6eull]

Add a way to customize typescript worker in module workers, avoiding importScripts (which the customWorkerPath uses to extend the typescript worker).

Hoping to provide some progress to #3151.

[x6eull]

@microsoft-github-policy-service agree

[hediet]

Afaik this approach does not work, as createData must be serializable. You cannot send over your customization function from the page to the worker.

[hediet]

Ah I think I understand, you want to provide a replacement for ts.worker.ts that calls create. But TypeScriptWorker is exported already by vs/language/typescript/tsWorker, so why don't you just implement your own create function that imports the exported TypeScriptWorker? This class is not exported in the ESM build.

[hediet]

I think it is a little bit ugly that you pass in unserializable data into the create function to override the TypeScriptWorker (and I hope nobody tries to pass in this data from the host side that creates the worker), but I don't see a much nicer solution.

[x6eull]

@microsoft-github-policy-service agree

[hediet]

I actually think #3488 is a better solution.

[x6eull]

I had no idea that createData must be serializable when I created the pr. I couldn't build a complete package and test it, so I just followed the step of customWorkerPath. If createData must be serializable, this approach won't work since I intend to use it in the script that create the worker (as well as the editor).

[hediet]

If createData must be serializable,

It does not have to be serializable when called from a script that imports the worker, but the data the host passes in has to be serializable. So it would have worked in your use-case, but it could confuse users.
#3488 just exports everything needed for a solution that does not cause this confusion.

Thanks for coming up with this PR anyway! :)