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JavaScript Asynchronous Programming with JavaScript Understanding Promises Handle Multiple Promises with Promise.all

Posted by Yaxin Yuan
Yaxin Yuan
11,191 Points

Why do we have to make getProfile() return promise at all?

Based on what I read here:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

the function passed in as an argument in then() itself does not have to return promise, then() function will "convert" the result of that function into a promise anyway, so why don't we just leave it as a regular function returning an array of profiles(instead of array of promise)?

1 Answer

Fernando Boza
Fernando Boza
25,384 Points

Hey Yaxin Yuan the reason we use Promise.all() is that it ONLY returns an array of promises when we have multiple promises and we want to only know when the promises have successfully finished.

Great question btw you can read it here

and

https://stackoverflow.com/questions/38180080/when-to-use-promise-all