CODEWITHSUNDEEP
javascriptecmascript-6async-awaitbabeljsecmascript-2017
Kosmetika
Kosmetika

Reputation: 21304

ES2017 Async/await functions - do they work only with promises?

I started using async/await ES7 functions in my js applications (transpiled by Babel).

Correct me if wrong, but do they work only with Promises? If yes, this means that I need to wrap regular callback functions into Promises (what I'm currently doing btw).

Upvotes: 13

Views: 2755

Answers (2)

Benjamin Gruenbaum
Benjamin Gruenbaum

Reputation: 276286

The current (and likely final) async/await proposal awaits promises and desugars into something like bluebird's Promise.coroutine with await playing the part of yield.

This makes sense, as promises represent a value + time and you're waiting for that value to become available. Note await also waits for promise like constructs in all other languages that include it like C# or Python (3.5+) .

Note that converting callback APIs to promises is very easy, and some libraries offer tools to do so in a single command. See How to convert an existing callback API to promises for more details.

Upvotes: 10

Evan Davis
Evan Davis

Reputation: 36592

Yes, you await a promise.

async function myFunction() {
  let result = await somethingThatReturnsAPromise();
  console.log(result); // cool, we have a result
}

http://pouchdb.com/2015/03/05/taming-the-async-beast-with-es7.html

Upvotes: 2

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