JS async/await - why does await need async?

user_1483977 0
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Why does using await need its outer function to be declared async?

For example, why does this mongoose statement need the function it's in to return a promise?

async function middleware(hostname, done) {
  try {
    let team = await Teams.findOne({ hostnames: hostname.toLowerCase() }).exec();
    done(null, team);
  } catch (err) { done(err); }
}

I see the runtime/transpiler resolving the Teams promise to it's value and async signaling it "throws" rejected promises.

But try/catch "catches" those rejected promises, so why are async and await so tightly coupled?

async-await asynchronous javascript
3 Answers

Because using await inside middleware function means the middleware function can't return a result immediately (it must wait until await is settled) and middleware function callers must wait until the promise (returned from middleware function) is settled.

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