freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-algorithm-scripting/finders-keepers.english.md

id, title, isRequired, challengeType

id	title	isRequired	challengeType
a6e40f1041b06c996f7b2406	Finders Keepers	true	5

Description

Create a function that looks through an array (first argument) and returns the first element in the array that passes a truth test (second argument). If no element passes the test, return undefined. Remember to use Read-Search-Ask if you get stuck. Try to pair program. Write your own code.

Instructions

Tests

tests:
  - text: '<code>findElement([1, 3, 5, 8, 9, 10], function(num) { return num % 2 === 0; })</code> should return 8.'
    testString: 'assert.strictEqual(findElement([1, 3, 5, 8, 9, 10], function(num) { return num % 2 === 0; }), 8, "<code>findElement([1, 3, 5, 8, 9, 10], function(num) { return num % 2 === 0; })</code> should return 8.");'
  - text: '<code>findElement([1, 3, 5, 9], function(num) { return num % 2 === 0; })</code> should return undefined.'
    testString: 'assert.strictEqual(findElement([1, 3, 5, 9], function(num) { return num % 2 === 0; }), undefined, "<code>findElement([1, 3, 5, 9], function(num) { return num % 2 === 0; })</code> should return undefined.");'

Challenge Seed

function findElement(arr, func) {
  let num = 0;
  return num;
}

findElement([1, 2, 3, 4], num => num % 2 === 0);

Solution

function findElement(arr, func) {
  let num;

  arr.some(e => {
    if (func(e)) {
      num = e;
      return true;
    }
  });

  return num;
}

findElement([1, 2, 3, 4], num => num % 2 === 0);