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Object.getOwnPropertyDescriptor

The Object.getOwnPropertyDescriptor() method returns a property descriptor for an own property (that is, one directly present on an object and not in the object's prototype chain) of a given object.

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

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
// }

Notes

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

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 5 Yes 4 8 12 5
Mobile
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support Yes Yes Yes 4 Yes Yes Yes
Server
Node.js
Basic support Yes

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptor