Periodically resolving a promise in javascript

Question

Let’s say I want to resolve some promise every 2 seconds AFTER the function is run.

I tried a pattern like this at first: setInterval(MyAsyncFunction, 2000), but of course this does not wait for the promise to resolve before calling the function again.

I also tried setInterval(async () => await MyAsyncFunction(), 2000), but this is basically the same thing since I’m just wrapping it in another promise that will resolve while the setInterval is ticking down.

Is there a way to do what I am trying to do with setInterval or is there some alternative way to do this using setTimeout?

Answer 1

A Promise resolves once only, so therefore cannot, by definition, resolve periodically.

If you define a delay function, which returns a promise that resolves after timeout ms...

const delay = timeout => new Promise(resolve => setTimeout(resolve, timeout));

you could use it in an async loop:

async function foo(){
    for(let i = 0; i < 100; ++i){
        console.log("azrael");
        await delay(2000);
    }
}