Reflect.getOwnPropertyDescriptor()

{{JSRef}} 

The Reflect.getOwnPropertyDescriptor() static method is like {{jsxref("Object.getOwnPropertyDescriptor()")}} . It returns a property descriptor of the given property if it exists on the object, {{jsxref("undefined")}}  otherwise.

{{InteractiveExample("JavaScript Demo: Reflect.getOwnPropertyDescriptor()")}} 

const object1 = {
  property1: 42,
};

console.log(Reflect.getOwnPropertyDescriptor(object1, "property1").value);
// Expected output: 42

console.log(Reflect.getOwnPropertyDescriptor(object1, "property2"));
// Expected output: undefined

console.log(Reflect.getOwnPropertyDescriptor(object1, "property1").writable);
// Expected output: true

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, {{jsxref("undefined")}} .

Exceptions

• {{jsxref("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 {{jsxref("Object.getOwnPropertyDescriptor()")}}  is how non-object targets are handled. Reflect.getOwnPropertyDescriptor() throws a {{jsxref("TypeError")}}  if the target is not an object, while Object.getOwnPropertyDescriptor() coerces it to an object.

Reflect.getOwnPropertyDescriptor() invokes the [[GetOwnProperty]] 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 {{jsxref("TypeError")}} . With {{jsxref("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

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Polyfill of Reflect.getOwnPropertyDescriptor in core-js
• {{jsxref("Reflect")}} 
• {{jsxref("Object.getOwnPropertyDescriptor()")}} 
• handler.getOwnPropertyDescriptor()