2634-filter-elements-from-array.js

/**
 * 2634. Filter Elements from Array
 * https://leetcode.com/problems/filter-elements-from-array/
 * Difficulty: Easy
 *
 * Given an integer array arr and a filtering function fn, return a filtered array filteredArr.
 *
 * The fn function takes one or two arguments:
 * arr[i] - number from the arr
 * i - index of arr[i]
 *
 * filteredArr should only contain the elements from the arr for which the expression
 * fn(arr[i], i) evaluates to a truthy value. A truthy value is a value where
 * Boolean(value) returns true.
 *
 * Please solve it without the built-in Array.filter method.
 */

/**
 * @param {number[]} arr
 * @param {Function} fn
 * @return {number[]}
 */
var filter = function(arr, fn) {
  const result = [];

  for (let i = 0; i < arr.length; i++) {
    if (fn(arr[i], i)) {
      result.push(arr[i]);
    }
  }

  return result;
};