How to append an item to an array in JavaScript

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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.