Skip to content

Remove Duplicates from Array in JavaScript

A common task required in JavaScript when dealing with arrays is the ability to preserve the array and at the same time remove duplicates from the array.

Remove Duplicates from Array in ES5

If you required older browser support, here’s a solution that uses ES5’s Array.reduce() method to remove duplicates from an array:

let items = ['a', 1, 'a', 'beachfront', 'avenue'];

let unique = items.reduce(function(a,b) {
  if (a.indexOf(b) < 0 ) {
  return a;

console.log(items); // ['a', 1, 'a', 'beachfront', 'avenue']
console.log(unique); // ['a', 1, 'beachfront', 'avenue']
Code language: JavaScript (javascript)

Remove Duplicates from Array in ES6

Starting with ES6, doing this is much easier using the new Set() constructor. The following example uses Set() along with ES6’s spread operator to remove duplicates from an array:

let items = ['a', 1, 'a', 'beachfront', 'avenue'];
let unique = [ Set(items)];

console.log(items); // ['a', 1, 'a', 'beachfront', 'avenue']
console.log(unique); // ['a', 1, 'beachfront', 'avenue']
Code language: JavaScript (javascript)

Solutions for More Complex Examples

Some solutions to this require more complex code. For example, what if you want to remove two objects that are identical? Or what if you want to sort the items while removing the duplicates? These are beyond the scope of this brief snippet, but you can view the following Stack Overflow threads for a number of different answers that work in older browsers:

Note: To the best of our knowledge, the information above and the snippet are accurate and up to date. However, in case you notice something wrong, please report snippet or leave a comment below.
View all Snippets
Louis Lazaris

Inline Feedbacks
View all comments

Or start the conversation in our Facebook group for WordPress professionals. Find answers, share tips, and get help from other WordPress experts. Join now (it’s free)!

Would love your thoughts, please comment.x

Most Searched Articles

Best JavaScript Libraries and Frameworks: Try These 14 in 2024

In this post, we look at the best JavaScript libraries and frameworks to try out this year. Why? Well, with JavaScript being available in every web browser, this makes it the most accessible programming language of ...

20 Best Free WordPress Themes for 2024 (Responsive, Mobile-Ready, Beautiful)

If you're looking for only the best free WordPress themes in the market for this year, then you're in the right place. We have more than enough such themes for you right ...

12 Best WordPress Hosting Providers of 2024 Compared and Tested

Looking for the best WordPress hosting that you can actually afford? We did the testing for you. Here are 10+ best hosts on the market ...

Handpicked Articles

How to Make a WordPress Website: Ultimate Guide for All Users – Beginners, Intermediate, Advanced

Many people wonder how to make a WordPress website. They’ve heard about WordPress, its incredible popularity, excellent features and designs, and now they want to join the pack and build a WordPress website of their own. So, where does one get ...

How to Start an Ecommerce Business: Ultimate Guide for 2024

Is this going to be the year you learn how to start an eCommerce business from scratch? You’re certainly in the right place! This guide will give you a roadmap to getting from 0 to a fully functional eCommerce business. ...