2634. Filter Elements From Array

Given an integer array arr and a filtering function fn, return a new array with a fewer or equal number of elements.

The returned array should only contain elements where fn(arr[i], i) evaluated to a truthy value.

Please solve it without the built-in Array.filter method.

Example 1.

Input: arr = [0,10,20,30], fn = function greaterThan10(n) { return n > 10; }
Output: [20,30]
Explanation:
const newArray = filter(arr, fn); // [20, 30]
The function filters out values that are not greater than 10

Example 2

Input: arr = [1,2,3], fn = function firstIndex(n, i) { return i === 0; }
Output: [1]
Explanation:
fn can also accept the index of each element
In this case, the function removes elements not at index 0

Example 3

Input: arr = [-2,-1,0,1,2], fn = function plusOne(n) { return n + 1 }
Output: [-2,0,1,2]
Explanation:
Falsy values such as 0 should be filtered out

Approach

given function should have 2 arguments n , index
given function returns Boolean value if meet the requirements
when function returns true pushes elements to the filtered array

How i Solved the Problem

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

  // Brutely filters array
  for (let i = 0; i < arr.length; i++) {
    if (fn(arr[i], i)) filtered.push(arr[i]);
  }

  return filtered;
};