How to use await instead of . then() in Javascript?

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I have this asynchronous code:

const delay = () => new Promise(resolve => setTimeout(resolve, 1000));


async function umPorSegundo(){
    console.log(await delay(), '1s')
    console.log(await delay(), '2s')
    console.log(await delay(), '3s')
}

umPorSegundo();

The delay is done correctly, but the console always returns undefined before. How to make it return only the seconds?

javascript async async-await
  • 1

    console.log(await delay() || '1s');

1 answer

3


The console is logging in undefined because the function delay returns nothing (what is undefined).

For example:

function test() {
  // Não retorna nada.
}

console.log(test()); // undefined

If you want to modify the function delay to return the seconds, you will need to change her code:

const delay = () => new Promise(resolve => setTimeout(() => resolve(1000), 1000));

In that case, the Promise will be solving the value 1000 (1000 milliseconds is equal to 1 second). You can modify the resolve so that the promise will solve any other value...

To learn more about the Promises, read here.

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