Cloning Arrays in JavaScript

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There are a few ways to clone an array in JavaScript,

Object.assign

Object.assign allows us to make a shallow copy of any kind of object including arrays.

For example:

const a = [1,2,3];
const b = Object.assign([], a); // [1,2,3]

Array.slice

The Array.slice function returns a copy of the original array.

For example:

const a = [1,2,3];
const b = a.slice(0); // [1,2,3]

Array.from

The Array.slice function returns a copy of the original array. It takes array like objects like Set and it also takes an array as an argument.

const a = [1,2,3];
const b = Array.from(a); // [1,2,3]

Spread Operator

The fastest way to copy an array, which is available with ES6 or later, is the spread operator.

const a = [1,2,3];
const b = [...a]; // [1,2,3]

JSON.parse and JSON.stringify

This allows for deep copy of an array and only works if the objects in the array are plain objects. It can be used like this:

const a = [1,2,3];
const b = JSON.parse(JSON.stringify(a)); // [1,2,3]