The Difference Between ForEach and Map in JavaScript

The Difference Between ForEach and Map in JavaScript

JavaScript methods: forEach VS map with examples.

Introduction

JavaScript has methods to iterate through arrays. The forEach method and the map method are the two most commonly used. A lot of beginners think that these two methods are the same in the way they work because they both do an iteration and output something.

In this article, we will learn about forEach and map in JavaScript by covering the differences between them. Let’s get right into it.

The forEach method

The method forEach is a higher-order function because it takes a callback as its argument. It is used to iterate through array elements and it returns undefined. The callback can take three arguments(element, value, and index).

Here is an example:

let arr = [1, 2, 3 , 4];

//ES5:
arr.forEach(function(elem){
 return elem * 2;
});
//returns "undefined"
//ES6:
arr.forEach(elem => elem * 2);
//returns "undefined"

As you can see, above the method forEach returns undefined . It does not mutate the array, but it can mutate it with the callback.

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