Object.getPrototypeOf()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The Object.getPrototypeOf() static method returns the prototype (i.e., the value of the internal [[Prototype]] property) of the specified object.

Try it

const prototype1 = {};
const object1 = Object.create(prototype1);

console.log(Object.getPrototypeOf(object1) === prototype1);
// Expected output: true

Syntax

Object.getPrototypeOf(obj)

Parameters

obj: The object whose prototype is to be returned.

Return value

The prototype of the given object, which may be null.

Examples

Using getPrototypeOf

const proto = {};
const obj = Object.create(proto);
Object.getPrototypeOf(obj) === proto; // true

Non-object coercion

In ES5, it will throw a TypeError exception if the obj parameter isn't an object. In ES2015, the parameter will be coerced to an Object.

Object.getPrototypeOf("foo");
// TypeError: "foo" is not an object (ES5 code)
Object.getPrototypeOf("foo");
// String.prototype                  (ES2015 code)

Specifications

Specification
ECMAScript® 2026 Language Specification # sec-object.getprototypeof