JavaScript (ES2026) reference · Object Methods

JavaScript Object.setPrototypeOf() Method

Change the prototype of an existing object. It is slow in most engines; prefer Object.create() or classes.

JavaScript (ES2026) Since ES2015

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Syntax

Object.setPrototypeOf(obj, prototype)

Parameter	Description
`obj`	The object to inspect or change.
`prototype`	The new prototype, or `null`.

The object.

Add inherited methodsTry it yourself

const base = { greet() { return "hi " + this.name; } };
const user = { name: "Ada" };
Object.setPrototypeOf(user, base);
console.log(user.greet());

Output

hi Ada

Remove all inherited methodsTry it yourself

const o = Object.setPrototypeOf({ a: 1 }, null);
console.log(typeof o.toString);

Output

undefined

Version	Change
JavaScript ES2015	Added

Object.getPrototypeOf() · Return the prototype of an object: the object it inherits methods and properties from, or null.
Object.create() · Create a new object with the given prototype (or null for an object with no inherited properties at all).
JavaScript Objects · tutorial