Reflect.getOwnPropertyDescriptor()

The Reflect.getOwnPropertyDescriptor() static method is like 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 as an own property of target; otherwise, undefined.

Exceptions

TypeError
- : Thrown if target is not an object.

Description

Reflect.getOwnPropertyDescriptor() provides the reflective semantic of retrieving the property descriptor of an object. The only difference with Object.getOwnPropertyDescriptor is how non-object targets are handled. Reflect.getOwnPropertyDescriptor() throws a TypeError if the target is not an object, while Object.getOwnPropertyDescriptor() coerces it to an object.

Reflect.getOwnPropertyDescriptor() invokes the <span class="createlink">GetOwnProperty</span> object internal method of target.

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 with 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 }