Reflect.getOwnPropertyDescriptor() - JavaScript 编辑

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.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

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 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 in the target 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 target 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
ECMAScript (ECMA-262) The definition of 'Reflect.getOwnPropertyDescriptor' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• Reflect
• Object.getOwnPropertyDescriptor()