Object.getPrototypeOf

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

Syntax

Object.getPrototypeOf(obj)

Parameters

obj

The object whose prototype is to be returned.

Return value

The prototype of the given object. If there are no inherited properties, null is returned.

Examples

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

Notes

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	Status	Comment
ECMAScript 5.1 (ECMA-262) The definition of 'Object.getPrototypeOf' in that specification.	Standard	Initial definition.
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Object.getProtoypeOf' in that specification.	Standard
ECMAScript 2017 Draft (ECMA-262) The definition of 'Object.getProtoypeOf' in that specification.	Draft

Browser compatibility

Opera-specific notes

Even though older Opera versions don't support Object.getPrototypeOf() yet, Opera supports the non-standard __proto__ property since Opera 10.50.

See also

• Object.prototype.isPrototypeOf()
• Object.setPrototypeOf()
• Object.prototype.__proto__
• John Resig's post on getPrototypeOf
• Reflect.getPrototypeOf()