Reflect.getOwnPropertyDescriptor()
The static Reflect
.getOwnPropertyDescriptor()
method is similar to Object.getOwnPropertyDescriptor()
. It returns a property descriptor of the given property if it exists on the object, undefined
otherwise.
Syntax
Reflect.getOwnPropertyDescriptor(target, propertyKey)
Parameters
target
- The target object in which to look for the property.
propertyKey
- The name of the property to get an own property descriptor for.
Return value
A property descriptor object if the property exists in the given target object; otherwise, undefined
.
Exceptions
A TypeError
, if target
is not an Object
.
Description
The Reflect.
getOwnPropertyDescriptor method returns a property descriptor of the given property if it exists on the object, undefined
otherwise. The only difference to Object.getOwnPropertyDescriptor()
is how non-object targets are handled.
Examples
Using Reflect.getOwnPropertyDescriptor()
Reflect.getOwnPropertyDescriptor({x: "hello"}, "x"); // {value: "hello", writable: true, enumerable: true, configurable: true} Reflect.getOwnPropertyDescriptor({x: "hello"}, "y"); // undefined Reflect.getOwnPropertyDescriptor([], "length"); // {value: 0, writable: true, enumerable: false, configurable: false}
Difference to Object.getOwnPropertyDescriptor()
If the first argument to this method is not an object (a primitive), then it will cause a TypeError
. With Object.getOwnPropertyDescriptor
, a non-object first argument will be coerced to an object at first.
Reflect.getOwnPropertyDescriptor("foo", 0); // TypeError: "foo" is not non-null object Object.getOwnPropertyDescriptor("foo", 0); // { value: "f", writable: false, enumerable: true, configurable: false }
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Reflect.getOwnPropertyDescriptor' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Reflect.getOwnPropertyDescriptor' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 49 | 42 (42) | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | No support | 42.0 (42) | No support | No support | No support |
See also
License
© 2016 Mozilla 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/reflect/getownpropertydescriptor