Object

`Object.freeze`

Freezes an object, preventing new properties from being added, existing properties from being removed, and existing properties from being changed

Syntax

JavaScript

Object.freeze(obj)

Parameters

Parameter	Type	Description
obj	T	The object to freeze

Return Value

The same object that was passed in

Examples

Basic Usage

const obj = { name: 'Alice', age: 30 };
Object.freeze(obj);
obj.age = 31; // silently fails in non-strict mode
console.log(obj.age); // 30

Practical Example

const CONFIG = Object.freeze({
  API_URL: 'https://api.example.com',
  TIMEOUT: 5000,
});
// CONFIG.API_URL = 'x'; // TypeError in strict mode

Advanced Usage

const arr = Object.freeze([1, 2, 3]);
// arr.push(4); // TypeError
console.log(arr); // [1, 2, 3]

Understanding Object.freeze

The Object.freeze method in JavaScript freezes an object, preventing new properties from being added, existing properties from being removed, and existing properties from being changed. It belongs to the Object object and is one of the most widely used methods for working with object values in modern JavaScript and TypeScript applications.

The method signature is Object.freeze(obj). It accepts 1 parameter: obj. When called, it returns the same object that was passed in. Understanding when and how to use freeze() helps you write more expressive, readable code.

Common use cases for Object.freeze include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like object-isfrozen, object-seal, object-issealed, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for Object.freeze is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.