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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.