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What does a top-level async function return in JavaScript?

If I call an async function that doesn’t explicitly return anything from the await, will it return a resolved Promise? Or Void? Something else?

For example an IIFE like this, or this but it being called in the global scope by sync code:

(async myFunc() {
   const list = await someFunc();
   const anotherList = someOtherFunc(list);
   console.log(anotherList);
})();

I have it in my head that all async functions return a Promise.

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2

Answers


  1. 0

    If code inside the async IIFE is sync and no promise returned than it returns a resolved fullfilled promise. If it contains await or returns a promise it returns a pending promise:

    let promise = (async () => {

})();

console.log(promise.toString());

promise = (async () => {
   const list = await 1;
})();

console.log(promise.toString());

    enter image description here

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  2. 0

    Asynchronous functions are just a wrapper around the Promise object. Normally, one creates a promise and passes in a callback function. When ready, the programmer calls the then method, et cetera. When using the async keyword, it simply abstracts that system. Therefore, it will always return a promise, even if you return something else, because it isn’t actually returning what you return.

    console.log((async () => {
    const list = await someFunc();
    const anotherList = someOtherFunc(list);
    console.log(anotherList);
})().toString());

console.log((async () => {
    const list = await someFunc();
    const anotherList = someOtherFunc(list);
    console.log(anotherList);
    return "foo";
})().toString());
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