[tantalor]

> the Wasm-functions you call will return immediately

That can't be right. Doesn't JS block on the call, like any old function? The wasm function returns a value, not a promise/thenable. So if the wasm function takes a long time/forever, it will not "return immediately".

[brundolf]

I think by "immediately" he specifically meant "synchronously". He contrasted with web workers which run in separate threads, which means that they send messages back in an asynchronous promise.

[hombre_fatal]

They're expressing surprise that, unlike their experience with WebWorkers, you get to interface with Wasm/JS directly rather than through an async boundary.