freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-algorithm-scripting/finders-keepers/index.md

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Finders Keepers

Problem Explanation

We need to return the element from an array that passes a function. Both the function and the array are passed into our function findElement(arr, func).

Hint: 1

Looking through the array can be done with a for loop.

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Hint: 2

num is passed to the function. We will need to set it to the elements we want to check with the function.

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Hint: 3

Do not forget, if none of the numbers in the array pass the test, it should return undefined.

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Basic Solution

function findElement(arr, func) {
  let num = 0;
  
  for(var i = 0; i < arr.length; i++) {
    num = arr[i];
    if (func(num)) {
      return num;
    }
  }
  
  return undefined;
}

Code Explanation

• Challenge asks us to look through array. This is done using a for loop.
• The num variable is being passed into the function, so we set it to each index in our array.
• The pre-defined function already checks each number for us, so if it is "true", we return that num.
• If none of the numbers in the array pass the function's test, we return undefined.