Object.getOwnPropertyDescriptor()

The Object.getOwnPropertyDescriptor() method returns an object describing the configuration of a specific property on a given object (that is, one directly present on an object and not in the object's prototype chain). The object returned is mutable but mutating it has no effect on the original property's configuration.

Syntax

Object.getOwnPropertyDescriptor(obj, prop)

Parameters

obj
The object in which to look for the property.
prop
The name or Symbol of the property whose description is to be retrieved.

Return value

A property descriptor of the given property if it exists on the object, undefined otherwise.

Description

This method permits examination of the precise description of a property. A property in JavaScript consists of either a string-valued name or a Symbol and a property descriptor. Further information about property descriptor types and their attributes can be found in Object.defineProperty().

A property descriptor is a record with some of the following attributes:

value
The value associated with the property (data descriptors only).
writable
true if and only if the value associated with the property may be changed (data descriptors only).
get
A function which serves as a getter for the property, or undefined if there is no getter (accessor descriptors only).
set
A function which serves as a setter for the property, or undefined if there is no setter (accessor descriptors only).
configurable
true if and only if the type of this property descriptor may be changed and if the property may be deleted from the corresponding object.
enumerable
true if and only if this property shows up during enumeration of the properties on the corresponding object.

Examples

Using Object.getOwnPropertyDescriptor

var o, d;

o = { get foo() { return 17; } };
d = Object.getOwnPropertyDescriptor(o, 'foo');
// d is {
//   configurable: true,
//   enumerable: true,
//   get: /*the getter function*/,
//   set: undefined
// }

o = { bar: 42 };
d = Object.getOwnPropertyDescriptor(o, 'bar');
// d is {
//   configurable: true,
//   enumerable: true,
//   value: 42,
//   writable: true
// }

o = { [Symbol.for('baz')]: 73 }
d = Object.getOwnPropertyDescriptor(o, Symbol.for('baz')); 
// d is {
//   configurable: true,
//   enumerable: true,
//   value: 73,
//   writable: true
// }

o = {};
Object.defineProperty(o, 'qux', {
  value: 8675309,
  writable: false,
  enumerable: false
});
d = Object.getOwnPropertyDescriptor(o, 'qux');
// d is {
//   value: 8675309,
//   writable: false,
//   enumerable: false,
//   configurable: false
// }

Non-object coercion

In ES5, if the first argument to this method is not an object (a primitive), then it will cause a TypeError. In ES2015, a non-object first argument will be coerced to an object at first.

Object.getOwnPropertyDescriptor('foo', 0);
// TypeError: "foo" is not an object  // ES5 code

Object.getOwnPropertyDescriptor('foo', 0);
// Object returned by ES2015 code: {
//   configurable: false,
//   enumerable: true,
//   value: "f",
//   writable: false
// }

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Object.getOwnPropertyDescriptor' in that specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
getOwnPropertyDescriptorChrome Full support 5Edge Full support 12Firefox Full support 4IE Full support 9
Full support 9
Partial support 8
Notes
Notes In Internet Explorer 8, this was only supported on DOM objects and with some non-standard behaviors. This was later fixed in Internet Explorer 9.
Opera Full support 12Safari Full support 5WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 12Safari iOS Full support 5Samsung Internet Android Full support 1.0nodejs Full support Yes

Legend

Full support  
Full support
See implementation notes.
See implementation notes.

See also