Support async response function

[rochejul]

Hi

We could define a function when we want to return a custom response.

It should be great if it supports async response. Especially if we want to call a mock server.

It could be evolved like so:

setTimeout(async () => {
    let payload = response;

    if (typeof response === 'function') {
        payload = response(request);

        if (response.constructor.name === 'AsyncFunction' || payload instanceof Promise) {
            payload = await payload;
        }
    }

    resolve(new Response(url, status, payload));
}, +delay);

Thoughts?

[rChaoz]

I think this is a necessary addition. My use case is very simple - I want to read the JSON send by the client and create a response based on that. This is sadly not possible, as Request.json() returns a promise. Any workarounds for this?