JavaScript Object defineProperties() Method (original) (raw)

Last Updated : 12 Jul, 2024

The **Object.defineProperties() method in JavaScript is a standard built-in Object that defines a new or modifies existing properties directly on an object and it returns the object.

**Syntax:

Object.defineProperties(obj, props)

**Parameters:

• **Obj: This parameter holds the object on which the properties are going to be defined or modified.
• **Props: This parameter is an object whose own enumerable properties constitute descriptors for the properties to be defined or modified.

**Return Value:

• This method returns an object passed as an argument to the function.

**Example 1: In this example, we will define new properties to an object using the Object.defineProperties() method in JavaScript.

javascript `

const geek = {};

Object.defineProperties(geek, { prop1: { value: "geeksforgeeks", writable: true }, prop2: {} });

console.log(geek.prop1); console.log(geek.prop2);

`

**Output:

"geeksforgeeks"
undefined

**Example 2: In this example, we will define new properties and modify some properties of an object using the Object.defineProperties() method in JavaScript.

javascript `

let geek = {}; Object.defineProperties(geek, { 'prop1': { value: "Geeks", writable: true }, 'prop2': { value: 'Hello', writable: false } }); console.log(geek.prop2); console.log(geek.prop1);

const geek1 = {}; Object.defineProperties(geek1, { prop1: { value: "Hi", value: "Hello", value: "Namaste", }, prop2: { value: " And ", }, prop3: { value: "learn", value: "Stay Safe", } });

console.log(geek1.prop1, geek1.prop2, geek1.prop3);

`

**Output:

"Hello"
"Geeks"
"Namaste" " And " "Stay Safe"

We have a complete list of Javascript Object methods, to check those please go through this JavaScript Object Complete Reference article.

**Supported Browsers:

The browsers supported by Object.defineProperties() method are listed below:

• Google Chrome
• Mozilla
• Opera
• Safari

What does the Object.defineProperties() method do in JavaScript?

The Object.defineProperties() method defines new or modifies existing properties directly on an object, returning the object.

Can Object.defineProperties() be used to freeze properties?

You can create non-writable and non-configurable properties using Object.defineProperties(), effectively making them immutable.

How does Object.defineProperties() handle deeply nested properties?

Object.defineProperties() only defines or modifies properties at the top level of the object. It does not traverse nested objects.

How does Object.defineProperties() interact with strict mode?

In strict mode, attempting to define or modify properties in a way that violates property attributes will throw an error.

What is the most common use of the Object.defineProperties() method?

• **Batch Property Definition: Defining multiple properties with specific attributes at once.
• **Controlled Property Behavior: Customizing property behavior with attributes like writable, enumerable, and configurable.
• **Implementing Getters and Setters: Creating dynamic properties with getter and setter functions.
• **Updating Object Structures: Modifying and updating properties of existing objects efficiently.