How do you clone an object or array in JavaScript?

Question

How do you clone an object or array in JavaScript?

Answer

You can clone objects and arrays using several methods:

Using spread operator:

const arr = [1, 2, 3];
const copy = [...arr];

Using Object.assign():

const user = { name: 'Ali' };
const clone = Object.assign({}, user);

Deep copy example:

const deepClone = JSON.parse(JSON.stringify(obj));

Real-World Example

When managing React state, always clone objects or arrays before updating them to maintain immutability.

Quick Practice

Clone an array [10, 20, 30], modify its first element, and confirm the original array isn’t affected.

Summary

Use spread or Object.assign for shallow copies; use JSON methods or libraries for deep cloning.