Function not returning the expected result

user_11965086 0
Viewed 128

I have written a function to search an array and log a number(x) if it is found. The code below works as expected and 1 is logged.

let myArr = [54, 23, 499, 342, 1, 44];
let x = 1;

let searchNumber = (arr) => {
  arr.forEach(ele => {
    if (ele == x) {
      console.log(ele);
    }
  })
};

searchNumber(myArr);

I'd like to now return the number that I assign to variable x. Expecting y to be assigned 499 but when I log y it returns undefined. Where am I going wrong?

let myArr = [54, 23, 499, 342, 1, 44];
let x = 499;

let searchNumber = (arr) => {
  arr.forEach(ele => {
    if (ele == x) {
      return ele;
    }
  })
};

let y = searchNumber(myArr);
javascript
5 Answers

return ele inside forEach callback is not the return of the searchNumber function.

forEach executes a provided function once for each array element so return ele inside that will act like return to that provided function inside forEach.

It does not repesent the return to the main function.

In this case, it's better to use for loop.

let myArr = [54, 23, 499, 342, 1, 44];
let x = 499;

let searchNumber = (arr) => {
  for (let i = 0; i < arr.length; i ++) {
    if (arr[i] == x) {
      return arr[i];
    }
  }
};

let y = searchNumber(myArr);
console.log(y);

user_82028500

If you look at the placement of the return statement, it is actually within the arrow function being called for each element (ele => {...}). No value is actually being returned from the scope of the function searchNumber.

Try creating a variable in the scope of searchNumber and modifying it from arr.forEach() instead:

let myArr = [54, 23, 499, 342, 1, 44];
let x = 499;

let searchNumber = (arr) => {
    let val = null;
    arr.forEach(ele => {
        if (ele == x) {
            val = ele;
        }
    });
   return val;
};

let y = searchNumber(myArr);
user_100561780
user_112558010

.find will return the matching element:

let myArr = [54, 23, 499, 342, 1, 44];
let x = 499;

let searchNumber = (arr) => arr.find(ele => ele == x);

let y = searchNumber(myArr);

console.log(y);

user_74863130

what you are looking here is probably the find function.

let searchNumber = (arr) => arr.find(e => e === x);

let y = searchNumber(myArr);
user_96237260
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