Reflect.getOwnPropertyDescriptor()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2016.
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.
Try it
const object = {
property1: 42,
};
console.log(Reflect.getOwnPropertyDescriptor(object, "property1").value);
// Expected output: 42
console.log(Reflect.getOwnPropertyDescriptor(object, "property2"));
// Expected output: undefined
console.log(Reflect.getOwnPropertyDescriptor(object, "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, undefined.
Exceptions
TypeError-
Thrown if
targetis 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 [[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 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 |
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| ECMAScript® 2027 Language Specification # sec-reflect.getownpropertydescriptor |
Browser compatibility
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Legend
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- Full support
- Full support