Our volunteers haven't translated this article into Tiếng Việt yet. Join us and help get the job done!
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 ES6, 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); // {configurable:false, enumerable:true, value:"f", writable:false} // ES6 code
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 2017 Draft (ECMA-262) The definition of 'Object.getOwnPropertyDescriptor' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 5 | 4.0 (2) | 8 | 12 | 5 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | ? | ? | ? | ? | ? |