CODEWITHSUNDEEP
javascriptecmascript-6
Ejonas GGgg
Ejonas GGgg

Reputation: 476

Why do async functions return promise of values not values directly?

I now understand that async functions return promises of values not values directly. But what I don't understand is what the point of doing that in the first place. As far as I understand, async functions are used to synchronize code inside them, now after we got the value from a promise using the await statement inside the async function, why should we return another promise? Why don't we just return the result directly or return void?

Upvotes: 0

Views: 59

Answers (3)

Bergi
Bergi

Reputation: 664307

Yes, async function are used to sequentialise the code inside them. They do not - cannot - stop the code execution outside of them. As you probably remember, blocking is bad. You cannot get the result from the future of course, but you don't want to stop the world just to wait for that function to finish either. And that's why when you call such a function, you get back a promise that you either await, or can schedule a callback on and do other things while it waits.

Upvotes: 1

Estus Flask
Estus Flask

Reputation: 222369

async functions are used to synchronize code inside them

They aren't. async functions provide syntactic sugar for promises, thus eliminating the need to use callbacks. async function acts exactly like regular function that returns a promise.

There's no way how the result can be returned synchronously from asynchronous function.

If the result should be returned from async function, it should be called and awaited inside another async function, and so on - possibly up to application entry point.

Upvotes: 2

Suren Srapyan
Suren Srapyan

Reputation: 68635

Because you can't know when the asynchronous call will be done. So it just returns a promise to let you make your rest logic with asynchronous call by making then-s chain.

Upvotes: 1

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