← flaviocopes.com

How to append an item to an array in JavaScript

Published May 25 2018

Psssst! The 2023 WEB DEVELOPMENT BOOTCAMP is starting on FEBRUARY 01, 2023! SIGNUPS ARE NOW OPEN to this 10-weeks cohort course. Learn the fundamentals, HTML, CSS, JS, Tailwind, React, Next.js and much more! ✨

Append a single item

To append a single item to an array, use the push() method provided by the Array object:

const fruits = ['banana', 'pear', 'apple']
fruits.push('mango')

push() mutates the original array.

To create a new array instead, use the concat() Array method:

const fruits = ['banana', 'pear', 'apple']
const allfruits = fruits.concat('mango')

Notice that concat() does not actually add an item to the array, but creates a new array, which you can assign to another variable, or reassign to the original array (declaring it as let, as you cannot reassign a const):

let fruits = ['banana', 'pear', 'apple']
fruits = fruits.concat('mango')

Append multiple items

To append a multiple item to an array, you can use push() by calling it with multiple arguments:

const fruits = ['banana', 'pear', 'apple']
fruits.push('mango', 'melon', 'avocado')

You can also use the concat() method you saw before, passing a list of items separated by a comma:

const fruits = ['banana', 'pear', 'apple']
const allfruits = fruits.concat('mango', 'melon', 'avocado')

or an array:

const fruits = ['banana', 'pear', 'apple']
const allfruits = fruits.concat(['mango', 'melon', 'avocado'])

Remember that as described previously this method does not mutate the original array, but it returns a new array.

I write books for developers 👇🏼