Await in async functions works for any thenable

1 min read

This post is part of my Today I learned series in which I share all my learnings regarding web development.

async/await makes it possible to write asynchronous JavaScript that looks synchronous. It helps to fight the "callback hell". But what statements can we actually use in combination with await?

Šime Vidas and Axel Rauschmayer had a really interesting Twitter conversation recently. So let's look at some snippets.

(async () => { console.log(await 'foo'); })(); // 'foo'
(async () => { console.log(await 5); })();     // 5

It turns out that you can really await anything. I didn't know that. This is one of these tiny JS details I really like to discover. If you await something that's not a promise it will return the actual value.

let thenable = {
  then: (fn) => {
    fn('jup')
  }
};

(async () => { console.log(await thenable); })() // 'jup'

And... it doesn't have to be a promise. A thenable (anything that includes a function called then) works also fine. So thanks Šime and Axel for having these conversations in public.

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