Apply Transform Over Each Element in Array - 2635

🔗LC2635 🟢 Easy 🧩 Pattern – Array Transformations

📅 Day 5/30 Days of JavaScript

Given an integer array arr and a mapping function fn, return a new array with a transformation applied to each element.

The returned array should be created such that returnedArray[i] = fn(arr[i], i).

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

Example

Input: arr = [1,2,3], fn = function plusone(n) { return n + 1; }
Output: [2,3,4]
Explanation:
const newArray = map(arr, plusone); // [2,3,4]
The function increases each value in the array by one.

Solution

TLDR – write a polyfill for Array.map.

/**
 * @param {number[]} arr
 * @param {Function} fn
 * @return {number[]}
 */
var map = function (arr, fn) {
    const newArray = [];
    for (let i = 0; i < arr.length; i++) {
        newArray[i] = fn(arr[i], i);
    }
    return newArray
};

Apply Transform Over Each Element in Array – 2635

Example

Solution