Deep Clone an Object in JavaScript

structuredClone (recommended)

The built-in structuredClone() handles nested objects, arrays, Date, Map, Set, RegExp, and circular references out of the box:

const original = {
  a: 1,
  b: {
    c: 2,
    d: [3, 4]
  },
  date: new Date(),
};

const cloned = structuredClone(original);

console.log(cloned.b === original.b); // false
console.log(cloned.date instanceof Date); // true

structuredClone does not copy functions, DOM nodes, or prototype chains. If your object contains those, use the manual approach below.

Manual Fallback

A recursive approach for environments without structuredClone or when you need custom logic:

function deepClone(obj) {
  if (obj === null || typeof obj !== 'object') {
    return obj;
  }

  if (Array.isArray(obj)) {
    return obj.map(deepClone);
  }

  return Object.fromEntries(
    Object.entries(obj)
      .map(([key, value]) => [key, deepClone(value)])
  );
}

This manual version does not handle Date, Map, Set, or circular references. Prefer structuredClone() when possible.