Why does this promise resolve when I am not awaiting it

November 10, 2021

I have the following promise, but it seems to resolve without me even awaiting it if I run this code in ts playground.

const promises = [later(1000)];


function later(delay:number) {
    return new Promise<void>(function(resolve) {
        setTimeout(() => {
          console.log('test');
          resolve();
        }, delay);
    });
}

I only want it to execute when I call

await Promise.all(promises);

>Solution :

As other posts/comments said, later(1000) is evaluated right away and don’t wait for your await Promise.all call to run the promise code.

you could achieve that by doing the following:

const promises = [() => later(1000)];

function later(delay:number) {
    return new Promise<void>(function(resolve) {
        setTimeout(() => {
          console.log('test');
          resolve();
        }, delay);
    });
}

await Promise.all(promises.map(f => f()));