Javascript Async with map

Asked Jan 21 '21 at 18:15

Active Jan 21 '21 at 18:54

Viewed 53 times

This is a silly example, I'm not good at syntax I try to understand how to make it work with async as it doesn't (beware I need the map):

  const list = ["hello", "world"]
    

  async function test() {

    let allTexts = Promise.all(list.map(async word => word.upperCase()));
    return allTexts;
  }

  test().then(result => alert(result.join('')))

Solved through comments below : use then + Use toUpperCase instead. – evolutionxbox

edited Jan 21 '21 at 18:54

asked Jan 21 '21 at 18:15

user310291

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`test` will only return a promise, so that's what you call `toString()` on. You need to `await test()` or `test.then(result => alert(result))` – VLAZ Jan 21 '21 at 18:16
The inner function call doesn't need to be flagged `async` unless it needs to `await`, which apparently it doesn't. Is `upperCase()` an async function? That would be strange. – tadman Jan 21 '21 at 18:21
Is the `alert()` call within an `async` function? If not, you need the `.then()` chaining. – tadman Jan 21 '21 at 18:22
Does this answer your question? [How do I return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) – evolutionxbox Jan 21 '21 at 18:34
use `alert` inside the `then`. – evolutionxbox Jan 21 '21 at 18:35
@VLAZ I tried alert(test().then(result => result.join(''))) but doesn't work ? still a promise object... – user310291 Jan 21 '21 at 18:36
@tadman you're right it doesn't but in real I may need. – user310291 Jan 21 '21 at 18:38
@evolutionxbox I just tried see update but still doesn't work – user310291 Jan 21 '21 at 18:43
1

`word.upperCase` is incorrect and will throw an error. Use `toUpperCase` instead. – evolutionxbox Jan 21 '21 at 18:46
@evolutionxbox oh sh... that's what that stupid ! thanks :) – user310291 Jan 21 '21 at 18:47
The original async issue is solved by the link I gave. – evolutionxbox Jan 21 '21 at 18:48
@evolutionxbox ah sorry I looked at it but was so lengthy I couldn't see ;) – user310291 Jan 21 '21 at 18:49
1

It's good to read it. Even if it is quite lengthy – evolutionxbox Jan 21 '21 at 18:50

Javascript Async with map

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