Object.getOwnPropertyDescriptor()

{{JSRef}} 

The Object.getOwnPropertyDescriptor() static method returns an object describing the configuration of a specific property on a given object (that is, one directly present on an object and not in the object’s prototype chain). The object returned is mutable but mutating it has no effect on the original property’s configuration.

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

const object1 = {
  property1: 42,
};

const descriptor1 = Object.getOwnPropertyDescriptor(object1, "property1");

console.log(descriptor1.configurable);
// Expected output: true

console.log(descriptor1.value);
// Expected output: 42

Syntax

Object.getOwnPropertyDescriptor(obj, prop)

Parameters

• obj
  • : The object in which to look for the property.
• prop
  • : The name or {{jsxref("Symbol")}}  of the property whose description is to be retrieved.

Return value

A property descriptor of the given property if it exists on the object, {{jsxref("undefined")}}  otherwise.

Description

This method permits examination of the precise description of a property. A property in JavaScript consists of either a string-valued name or a {{jsxref("Symbol")}}  and a property descriptor. Further information about property descriptor types and their attributes can be found in {{jsxref("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 {{jsxref("undefined")}}  if there is no getter (accessor descriptors only).
• set
  • : A function which serves as a setter for the property, or {{jsxref("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

Using Object.getOwnPropertyDescriptor()

let o, d;

o = {
  get foo() {
    return 17;
  },
};
d = Object.getOwnPropertyDescriptor(o, "foo");
console.log(d);
// {
//   configurable: true,
//   enumerable: true,
//   get: [Function: get foo],
//   set: undefined
// }

o = { bar: 42 };
d = Object.getOwnPropertyDescriptor(o, "bar");
console.log(d);
// {
//   configurable: true,
//   enumerable: true,
//   value: 42,
//   writable: true
// }

o = { [Symbol.for("baz")]: 73 };
d = Object.getOwnPropertyDescriptor(o, Symbol.for("baz"));
console.log(d);
// {
//   configurable: true,
//   enumerable: true,
//   value: 73,
//   writable: true
// }

o = {};
Object.defineProperty(o, "qux", {
  value: 8675309,
  writable: false,
  enumerable: false,
});
d = Object.getOwnPropertyDescriptor(o, "qux");
console.log(d);
// {
//   value: 8675309,
//   writable: false,
//   enumerable: false,
//   configurable: false
// }

Non-object coercion

In ES5, if the first argument to this method is not an object (a primitive), then it will cause a {{jsxref("TypeError")}} . In ES2015, 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);
// Object returned by ES2015 code: {
//   configurable: false,
//   enumerable: true,
//   value: "f",
//   writable: false
// }

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• {{jsxref("Object.defineProperty()")}} 
• {{jsxref("Reflect.getOwnPropertyDescriptor()")}}