JavaScript Object.getOwnPropertyDescriptors()

let obj = {
  value: 11,
  get number() {
    return this.value;
  },
};

// get property descriptors for all the properties of obj
let objectProperties = Object.getOwnPropertyDescriptors(obj);

console.log(objectProperties);

Output

{
  value: { value: 11, writable: true, enumerable: true, configurable: true },
  number: {
    get: [Function: get number],
    set: undefined,
    enumerable: true,
    configurable: true
  }
}

getOwnPropertyDescriptors() Syntax

The syntax of the getOwnPropertyDescriptors() method is:

Object.getOwnPropertyDescriptors(obj)

Here, getOwnPropertyDescriptors() is a static method. Hence, we need to access the method using the class name, Object.

getOwnPropertyDescriptors() Parameters

The getOwnPropertyDescriptors() method takes in:

• obj - the object whose property descriptors we require.

getOwnPropertyDescriptors() Return Value

The getOwnPropertyDescriptors() method returns an object containing all the property descriptors of the given object.

Example 1: JavaScript Object.getOwnPropertyDescriptors()

let obj = {
  x: 10,
  get number() {
    return this.x;
  },
};

// get the property descriptors for all the properties of obj
let value = Object.getOwnPropertyDescriptors(obj);

console.log(value);

Output

{
  x: { value: 10, writable: true, enumerable: true, configurable: true },
  number: {
    get: [Function: get number],
    set: undefined,
    enumerable: true,
    configurable: true
  }
}

In the above example, the obj object contains the following properties:

• x - a property with a value of 10.
• number() - a getter method named which returns the value of x.

We then used the Object.getOwnPropertyDescriptors() method to get the descriptors for all the properties of obj i.e. x and number().

Example 2: getOwnPropertyDescriptors() for Shallow Copy

let obj = {
  x: 10,
  get number() {
    return this.x;
  },
};

// use getOwnPropertyDescriptors() for shallow copy
let cloneObj = Object.create(
  Object.getPrototypeOf(obj),
  Object.getOwnPropertyDescriptors(obj)
);

console.log(cloneObj); 

// Output: { x: 10, number: [Getter] }

In the above example, we can see that the getOwnPropertyDescriptors() method along with the create() method can help us create a shallow copy.

To demonstrate this, we first created an object named obj with the properties:

• x - a property with the value 10.
• number() - a getter method that returns the value of x.

Then, we created a shallow copy of obj (called cloneObj) using the create(), getPrototypeOf(), and getOwnPropertyDescriptors() methods.

let cloneObj = Object.create(
  Object.getPrototypeOf(obj),
  Object.getOwnPropertyDescriptors(obj)
);

As shown by the output, cloneObj is a shallow copy of obj since both objects are the same (they point to the same memory address).

Recommended Reading:

• Javascript Object.getOwnPropertyDescriptor()