How to Clear an Array in JavaScript

Clearing an array in JavaScript means removing all the elements in the array and leaving an empty array. Here's 3 ways to clear out an array:

array.length = 0

The simplest solution is to assign the array's length to the value of 0. The array length property is writable.

let array = [1, 2, 3, 4, 5];
array.length = 0;
array; // []

array.splice(0, array.length)

A more verbose approach is to use the splice() method. This function will return a copy of the array before deleting the entries, which is helpful if you want to do a reassignment before clearing the array.

let array = [1, 2, 3, 4, 5];
let anotherArray = array.splice(0, array.length);

anotherArray; // [1, 2, 3, 4, 5]
array; // []
anotherArray === array; // false

array = []

If you want to avoid mutating the arrays in place for immutability, you can overwrite the array with an empty array [].

let obj = { array: [1, 2, 3, 4, 5] };

obj = { ...obj, array: [] };
obj.array.length; // 0

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