ES2017异步/等待功能 - 它们只适用于承诺吗？

Question

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).

Answer 1

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.

Answer 2

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