Synchronously Wait for Message in Web-Worker

Question

Is there some way to synchronously wait for or check for a new message in a web-worker?

I have a large complicated body of code (compiled LLVM from emscripten) that I c

Answer 1

A crude hack to do this could be to use a synchronous API, such as the FileSystem API, and use a temporary file as a synchronising mechanism.

In your example, the emscripten code could issue a synchronous read on a file, while the UI thread writes to the same file, effectively unblocking the worker.

Answer 2

Can you break the sequence as follow without refactoring?

wrk.onmessage = function(e) {
    if (e.data.step === 'initial input') {
        doInitialWork(e.data.inputs)
    } else if (e.data.step === 'ui input') {
        doTheRest(e.data.uiData)
    }
}

The onmessage event will be blocked until the initial step execution stack is complete and the critical ui bits will only launch when and if the info is available.

Answer 3

No, unfortunately. There was some discussion of adding a way to block on a message from the parent page, but it went nowhere. I'll see if I can dig up the relevant mailing list thread.