CODEWITHSUNDEEP
javascriptasync-await
Carlos
Carlos

Reputation: 1277

How to call an async arrow function with await

If I define a function like this:

const getName = async () => await Promise.resolve('John');

When I try to call the getName function with async:

const name = await getName();
console.log(`Hi ${name}`);

It throws an error:

const name = await getName();
             ^^^^^

SyntaxError: await is only valid in async function

What I'm doing wrong?

Upvotes: 8

Views: 16496

Answers (1)

Quentin
Quentin

Reputation: 944205

const getName = async () => await Promise.resolve('John');

In the above, you have an async function (the arrow function) which uses await inside.

This is fine (albeit pointless as you could return the promise directly).

Here:

const name = await getName();

You use await again, and while the function on the right-hand side does return a promise, the function it appears inside is not async so it is not valid.

Put it inside an async function and it will be fine:

const getName = async() => await Promise.resolve('John');

const init = async() => {
  const name = await getName();
  console.log(`Hi ${name}`);
};

init();

As mentioned though, making getName async and awaiting inside is just a needlessly complex set of nested promises and you could simplify:

const getName = () => Promise.resolve('John');

const init = async() => {
  const name = await getName();
  console.log(`Hi ${name}`);
};

init();

Upvotes: 12

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