CODEWITHSUNDEEP
javascript
Asking
Asking

Reputation: 4200

Error from catch is not returned in JavaScript

I created the next function that should return the response, data and error in case if exists.

const login = function(cb) {
  fetch('https://jsonplaceholder.typicode.com/todos/1')
    .then((response) => {
      cb(null, null, response);
      return response.json();
    })
    .then((data) => {
      cb(data, null, null);
    })
    .catch((e) => {
      console.log('error inside catch:', e.message)
      cb(null, null, e)
    })
}

console.log(login((data, response, err) => console.log('data', data, 'response', response, 'error', err)))

So, I have to return all these values, but I can return just data. If I change this: https://jsonplaceholder.typicode.com/todos/1 to this: https://j123sonplaceholder.typicode.com/todos/1, to return err, I get undefined. The same issue is with response.
Question: How to get all these values?

Upvotes: 0

Views: 96

Answers (1)

dannyxnda
dannyxnda

Reputation: 1034

// you write
cb(response);
cb(data);
cb(error);

// so the data and error below make no sense
cb(response, data, error)

You passed 3 params to the cb when using it in console.log. But in the login function declaration, cb accepts only 1 param.
That means your console.log always prints 2 times, the first is the Response of API call and the second is the data (if success - then) or error (if fail - catch).

const arr = []
const login = function (cb) {
    // const arr = []; move array inside login function if not use outside
    fetch("https://jsonplaceholder.typicode.com/todos/1")
      .then((response) => {
        arr[0] = response;
        return response.json();
      })
      .then((data) => {
        arr[1] = data;
      })
      .catch((e) => {
        arr[2] = e;
      })
      .finally(() => {
        cb(...arr);
      });
  };

login((response, data, err) => console.log('response', response, 'data', data, 'error', err))
// console.log(arr[0]) // response
// console.log(arr[1]) // data
// console.log(arr[2]) // error

Upvotes: 3

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