DEV Community

Cover image for Introduction to Immer.js

Posted on

Introduction to Immer.js

What is Immer.js?

Immer.js is a library that provides a simple and intuitive API for working with immutable data in JavaScript applications. It is widely used in conjunction with state management libraries like Redux or Mobx. Immer.js allows developers to create a draft of the state that can be modified directly, and it takes care of producing a new immutable state with the changes applied.

Key Features

Immer.js offers several notable features:

  1. Immutability Made Easy: Immer.js simplifies the process of working with immutable data. Developers can directly modify the state as if it were mutable, and Immer.js takes care of producing a new immutable state.

  2. Automatic Cloning: The library automatically creates a new state tree by applying the changes, ensuring that the original state remains unaltered.

  3. Efficient Updates: Immer.js is designed to be highly efficient. It minimizes the amount of data copied during updates, making it suitable for handling large, complex state trees.

  4. React Integration: Immer.js seamlessly integrates with React and is widely used with libraries like Redux, making it a go-to choice for state management in React applications.

Code Examples

Let's look at some code examples to understand how Immer.js works. We'll use a simple example of a counter in a Redux-like store.

import produce from 'immer';

const initialState = { count: 0 };

const reducer = (state, action) => {
  return produce(state, (draftState) => {
    switch (action.type) {
      case 'INCREMENT':
        draftState.count += 1;
      case 'DECREMENT':
        draftState.count -= 1;
        return draftState;

// Usage
let state = initialState;
state = reducer(state, { type: 'INCREMENT' });
console.log(state); // { count: 1 }
Enter fullscreen mode Exit fullscreen mode

Popularity and Statistics

Immer.js has gained popularity in the React ecosystem with over 15,000 GitHub stars and numerous open-source projects using it for state management. It's actively maintained and receives updates and improvements regularly.
Image description

Immer.js vs. Redux

Both Immer.js and Redux are popular choices for managing application state, but they have different approaches and use cases. Let's compare these two state management solutions to help you decide which one suits your needs.


  • Immutability Made Easy: Immer.js simplifies working with immutable data. It allows developers to directly modify the state as if it were mutable, automatically creating a new immutable state with the changes applied.

  • Simplicity: Immer.js reduces boilerplate code, making state management code more readable and maintainable.

  • Efficiency: Immer.js is designed for efficiency, minimizing the amount of data copied during updates, which is crucial for performance in large applications.

  • React Integration: Immer.js seamlessly integrates with React, making it a popular choice for React applications.

  • Learning Curve: It has a relatively low learning curve, especially for developers familiar with mutable data.

  • Use Cases: Immer.js is well-suited for simpler state management needs and smaller applications.


  • Predictable State Management: Redux offers a predictable and centralized state management system. It enforces one-way data flow, which can be helpful in larger and more complex applications.

  • Middleware: Redux provides middleware support, allowing developers to add additional functionality such as logging, routing, or async operations.

  • Community and Ecosystem: Redux has a large community and a wide range of middleware and extensions available, making it a versatile choice.

  • DevTools: Redux DevTools provide powerful debugging capabilities for tracking state changes.

  • Learning Curve: Redux has a steeper learning curve, especially for those new to state management and immutable data concepts.

  • Use Cases: Redux is an excellent choice for larger, complex applications where predictability, scalability, and middleware support are essential.

When to Choose Immer.js

  • Use Immer.js when simplicity and ease of use are a priority, and you're working on smaller to medium-sized applications.
  • If you want to reduce the boilerplate code typically associated with immutability, Immer.js is an excellent choice.
  • When you prefer an approach that allows you to work with mutable-like data while still maintaining immutability.

When to Choose Redux

  • Choose Redux for larger and more complex applications that require a high level of predictability and centralization.
  • When you need extensive middleware support for routing, async operations, or custom extensions.
  • If you value a well-established ecosystem with a wide range of community-contributed packages and Redux DevTools for debugging.

In summary, the choice between Immer.js and Redux depends on the specific needs of your project. Immer.js simplifies state management and is great for smaller applications, while Redux offers a more structured and scalable solution, making it suitable for larger and more complex projects.


Immer.js is a valuable library for simplifying state management in JavaScript applications, especially those using React. Its intuitive API, automatic cloning, and efficient updates make it a solid choice for developers working with complex state structures. While it may have a learning curve for newcomers, it quickly becomes an indispensable tool in your state management toolkit.

If you liked my article, follow me on github -> Matek's github

Top comments (0)