Execute js file which uses Worker API

[GabrielePicco]

Version used

v3.0.0

Describe the bug

I'm trying to use a lib bundled with rollup, which uses the Worker api

To Reproduce

The line causing the issue is:

var browser$1 = Worker;

which fails with: JavaScriptErrorWrapperException: Worker is not defined

Expected behavior

Being able to use the Worker api

Additional context

I tried also to add export { Worker } from "worker_threads"; before bundling with rollup and embedding a worker mock with rollup-plugin-worker-factory, but without success.

• I'm also experimenting with some polyfill (e.g.: https://github.com/chjj/bthreads), but no luck so far.

[lahma]

Jint doesn't implement the Worker API so that's why it won't work.

[lahma]

Everything is possible in theory, but if any of the polyfills needs native constructs from say Node like threading, it's a dead-end. WASM will be probably the next roadblock at least like you've said.

[lahma]

You can of course implement and register the Worker API to Jint and try to bypass the need for polyfill, but that will be some work.

[Genteure]

Some ideas:

1. Implement Worker (either with polyfill or real multithreading) and WebAssembly (possibly with wasmtime-dotnet) in Jint.
2. Find an alternative library implemented in C#.
3. Explore the possibility of running that library in V8 by using ClearScript, assuming WebAssembly would just work in V8.
4. Run that library out of process, in another nodejs project. You could exchange data between the two process with something like HTTP API or gRPC.

If I were to do this, since I didn't find any equivalent library in C#, I would probably choose option 4.
Running out of process to me looks like would require the least effort, definitely work, and have predictable performance.

[GabrielePicco]

Thanks @lahma and @Genteure for the useful insights.
I'm trying to make the library usable for Unity, so unfortunately 2,3,4 I think are not viable options in my use-case.
I can use Jint in Unity, but not ClearScript. I will probably continue experimenting with option 1.

[GabrielePicco]

The worker polyfill doesn't seem to refer threading (it runs on the main thread), so perhaps that would work, even if implementing and registering the Worker API to Jint as @lahma suggested would be much better. I will do some investigation, as I'm not familiar with the Jint codebase. Thanks for the help.