Object.getOwnPropertyDescriptor()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
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.
Try it
const object = {
foo: 42,
};
const descriptor = Object.getOwnPropertyDescriptor(object, "foo");
console.log(descriptor.configurable);
// Expected output: true
console.log(descriptor.value);
// Expected output: 42
Syntax
Object.getOwnPropertyDescriptor(obj, prop)
Parameters
Return value
A property descriptor of the given property if it exists on the object,
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
Symbol and a property descriptor. Further information about property
descriptor types and their attributes can be found in
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-
trueif 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
undefinedif there is no getter (accessor descriptors only). set-
A function which serves as a setter for the property, or
undefinedif there is no setter (accessor descriptors only). configurable-
trueif and only if the type of this property descriptor may be changed and if the property may be deleted from the corresponding object. enumerable-
trueif 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 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
| Specification |
|---|
| ECMAScript® 2027 Language Specification # sec-object.getownpropertydescriptor |
Browser compatibility
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