JavaScript Object.assign() Method

Syntax

Object.assign(target, ...sources)

Parameters

Return value

The target object.

Examples

const defaults = { theme: "light", lang: "en" };
const settings = Object.assign({}, defaults, { lang: "de" });
console.log(settings, defaults);

{ theme: 'light', lang: 'de' } { theme: 'light', lang: 'en' }

const a = { nested: { x: 1 } };
const b = Object.assign({}, a);
b.nested.x = 99;
console.log(a.nested.x); // shallow copy: nested objects are shared
console.log({ ...a, extra: true });

99
{ nested: { x: 99 }, extra: true }

Version history

In other languages

• dict.update() · Python
• array_merge() · PHP
• array_replace() · PHP

Related

• Object.entries() · Return an array of an object's own enumerable [key, value] pairs, ready for for…of loops or array methods.
• Object.fromEntries() · Build an object from an iterable of [key, value] pairs, such as an array or a Map. The opposite of Object.entries().
• structuredClone() · Create a deep copy of a value, including nested objects, arrays, Dates, Maps and Sets. Functions can't be cloned.
• JavaScript Objects · tutorial