Why is my promise returning undefined?

Question

Background

I am trying to make a function that delays the execution of asynchronous functions by X ms.

For the purposes of this demonstration, the followi

Answer 1

Here's your problem:

        setTimeout(anUrl => {
            return new Promise( fulfil => {
                fulfil(asyncMock(anUrl));
            });
        }, throttleMs, url);

What you're doing here is you return a promise from the setTimeout callback. The return value of functions run by setTimeout are ignored so no one will get that value.