I just started using web workers using the workerpool library last week. There's something wildly satisfying about true parallelism in the browser.

I had an embarrassingly parallel problem with validating user drawn geometries against hundreds of thousands of others in real time and web workers is a godsend.

I'm assuming workerpool doesn't support closures? Judging from its GitHub page, it doesn't look like it.

From my own experience:

https://news.ycombinator.com/item?id=20192486

Well, you could put Function.toString() in a Blob, like this, but it feels kinda eval-y to me.

http://jsfiddle.net/tndm5hev/

Edit: looks like someone wrote an NPM package already:

https://www.npmjs.com/package/spawn-worker

This is how Task.js functions

https://github.com/icodeforlove/task.js

Which works on Node.js, and the browser. (Supports fork, worker_threads, and WebWorkers)

The advantage of this is that the workers become generic enough to run anything. Instead of having to have many "specialized" workers.

Performance-wise eval is not slow, and it is encapsulated inside of the actual worker. Obviously you don't want a user to be able to control any input. But for most cases we are talking about code related to processing, which involves hard coded functions, and the "external-data" being ArrayBuffers.