Here, we are going to discuss the property descriptors of an Object in JavaScript. The Object.getOwnPropertyDescriptor() method returns an object describing a specific property on a given object. A JavaScript object can be created in many ways and its properties can be called by using property descriptors for that object.
Syntax:
Object.getOwnPropertyDescriptor( obj, prop )
The Object.getOwnPropertyDescriptor() takes two parameters as input as described below:
- obj: It refers to the object name whose properties are to be described.
- prop: It defines the specific property in the object whose value is to be returned.
Return value: This method returns the property of the Object if it exists else it returns undefined.Â
Example: In the below example, an object Obj is created which consists of two properties property1 and property2. Â We use Object.getOwnPropertyDescriptor() property to return the attributes and values related to each property.
JavaScript
<script>       // Object     const Obj = {         property1: "neveropen",         property2: 12     };       const descriptor1 = Object         .getOwnPropertyDescriptor(Obj, 'property1');       const descriptor2 = Object         .getOwnPropertyDescriptor(Obj, 'property2');       console.log(descriptor1.configurable);     // expected output: true       console.log(descriptor1.enumerable);     // expected output: true       console.log(descriptor1.value);     // expected output: neveropen       console.log(descriptor2.value);     // expected output: 12   </script> |
Output:
true true neveropen 12
Descriptors:
A property descriptor of an object consists of some of the following attributes to define each property:
- value: It is the value associated with the property that is called
- writable: It indicates if the property can be changed or not. It only returns true if the property can be manipulated
- enumerable: If the property is visible during enumeration of the properties of the corresponding object, then it returns true.
- configurable: It indicates if the property descriptor can be changed or removed from the corresponding object.
Example: The below example describes the property attributes for property1 and property2 related to object Obj.
JavaScript
<script>     const Obj = {         property1: "neveropen",         property2: 12     };       const descriptor1 = Object         .getOwnPropertyDescriptor(Obj, 'property1');       const descriptor2 = Object         .getOwnPropertyDescriptor(Obj, 'property2');       console.log(descriptor1);     console.log(descriptor2); </script> |
Output:
{value: 'neveropen', writable: true, enumerable: true, configurable: true}
configurable: true
enumerable: true
value: "neveropen"
writable: true
[[Prototype]]: Object
{value: 12, writable: true, enumerable: true, configurable: true}
configurable: true
enumerable: true
value: 12
writable: true
[[Prototype]]: Object
