#2634 - Filter Elements from Array

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Problem Description

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.

Solution

/**
 * @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;
};