Catch a JavaScript error from a upper function

Question

I'm stuck with the following problem:

function upperFn(){
    FetchSomeThing() 
    .catch(err => { 
        console.log(err) 
    })
}

function lowerFn(){
    try {
        upperFn()
    }
    catch (err){
        //Here its not working anymore
        console.log(err) // Catch is never used
    }
}

So I've tried to return the error and even rethrow it but nothing work's. I would be very happy if someone can explain me how to catch this error in my lower function.

Thanks

Make `upperFn` return the promise, and then handle the promise rejection. You cannot handle asynchronous errors with a synchronous `try`/`catch`. — Bergi, Nov 05 '21 at 04:22

score 0 · Answer 1 · answered Nov 05 '21 at 03:15

0

I just figure out how to handle this probleme, simply by returning the whole function.

function upperFn(){
    return FetchSomeThing()
}

function lowerFn(){
    try {
        upperFn()
    }
    catch (err){
        //Here its working well
        console.log(err)
    }
}

answered Nov 05 '21 at 03:15

Laurent K

15
7

Isn't part of the point of promises to avoid *try..catch* (which id decidedly ugly), hence [*Promise.prototype.catch*](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch)? – RobG Nov 05 '21 at 03:46

score 0 · Answer 2 · answered Nov 05 '21 at 03:17

0

Simply throw the error in upperFunction and try-catch it in the lowerFunction

function FetchSomeThing() {
  return Promise.reject("Something goes wrong.");
}

function upperFn(){
  FetchSomeThing().catch(error => {
    throw error;
  })
}

function lowerFn(){
  try {
      upperFn()
  }
  catch (error) {
      //Here its not working anymore
      console.log(error) // Catch is never used
  }
}

lowerFn()

Working example: https://codesandbox.io/s/agitated-thunder-3s9qj

Output:

answered Nov 05 '21 at 03:17

Nawaf Khalifah

594
3
11

1

This is not working for me, it's sending me this err: Uncaught (in promise), but in my case the FetchSomeThing function is a firebase function that I can change – Laurent K Nov 05 '21 at 03:23
` err: Uncaught (in promise)` means there is an error but you don't catch it, can you please show me your code? Also the code in your question is not correct, it should be like this: ` FetchSomeThing() .catch(err => { console.log(err) })` – Nawaf Khalifah Nov 05 '21 at 04:25
https://codesandbox.io/s/infallible-haze-v6c80?file=/src/index.js – Laurent K Nov 05 '21 at 04:30
1

Please try this one: https://codesandbox.io/s/sharp-noyce-w8czu – Nawaf Khalifah Nov 05 '21 at 04:37
This way is working thanks for the time! – Laurent K Nov 05 '21 at 04:41
@LaurentK you're welcome, I'm gonna update the original answer. – Nawaf Khalifah Nov 05 '21 at 04:43

score -1 · Answer 3 · answered Nov 05 '21 at 03:08

-1

Maybe it's because you missed the error param after catch?

try {
  doSomeThing();
} catch (error) {
  console.error(error);
}

answered Nov 05 '21 at 03:08

Wang Ningning

1
1

I was not missing the err in my real code, but I have found a way to solve my problem – Laurent K Nov 05 '21 at 03:16

Catch a JavaScript error from a upper function

3 Answers3