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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 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 a string-valued name 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 = {};
Object.defineProperty(o, 'baz', {
  value: 8675309,
  writable: false,
  enumerable: false
});
d = Object.getOwnPropertyDescriptor(o, 'baz');
// 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

Specification Status Comment
ECMAScript 5.1 (ECMA-262)
The definition of 'Object.getOwnPropertyDescriptor' in that specification.
Standard Initial definition. Implemented in JavaScript 1.8.5.
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Object.getOwnPropertyDescriptor' in that specification.
Standard  
ECMAScript Latest Draft (ECMA-262)
The definition of 'Object.getOwnPropertyDescriptor' in that specification.
Living Standard  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support5 Yes48125
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support Yes Yes Yes Yes Yes Yes Yes

See also

文件標籤與貢獻者

 最近更新: fscholz,