Array.prototype.map

easycodingJavaScriptArraysPrototypes~10 min

Asked at Google, Meta, Amazon

Overview

Implement map(array, callback) that creates a new array with results of calling callback(element, index, array) on every element.

Examples

map([1,2,3], x => x * 2); // [2,4,6]

Solution

Reveal solution

function map(array, callback) {
  const r = [];
  for (let i = 0; i < array.length; i++) r.push(callback(array[i], i, array));
  return r;
}

array-prototype-map.js

Array.prototype.map

easycodingJavaScriptArrays

Overview

Implement map(array, callback) that creates a new array with results of calling callback(element, index, array) on every element.

Examples

map([1,2,3], x => x * 2); // [2,4,6]

Solution

Reveal solution

function map(array, callback) {
  const r = [];
  for (let i = 0; i < array.length; i++) r.push(callback(array[i], i, array));
  return r;
}

NameTopicDifficulty

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