Trying to understand async await

Question

I'm trying to understand why this piece of code doesn't behave as I expect:

async function test() {
  await setTimeout(() => {
    console.log('done')
  }, 1000)

  console.log('it finished');
}


test();

This first prints it finished and then prints done afterwards. Shouldn't this code wait for the timeout to finish before executing console.log('it finished'); or have I misunderstood something?

why are you using `await` on `setTimeout`? it's not a promise — Tibebes. M, Oct 29 '20 at 11:50
you should have a look at promises and how they work in general — EugenSunic, Oct 29 '20 at 11:56
Does this answer your question? [How to setTimeout on async await call node](https://stackoverflow.com/questions/50091857/how-to-settimeout-on-async-await-call-node) And Maybe the title should be like _Trying to await setTimeout not working_ — Ulysse BN, Oct 29 '20 at 11:57

score 5 · Accepted Answer · answered Oct 29 '20 at 11:49

You can only usefully await a promise.

setTimeout returns a timeout id (a number) that you can pass to clearTimeout to cancel it. It doesn't return a promise.

You could wrap setTimeout in a promise…

async function test() {
  await new Promise( resolve => setTimeout(() => {
    console.log('done');
    resolve("done");
  }, 1000));

  console.log('it finished');
}


test();

Trying to understand async await

1 Answers1