Getting Started with Redux

It helps you write applications that behave consistently, run in different environments (client, server, and native), and are easy to test. On top of that, it provides a great developer experience, such as live code editing combined with a time traveling debugger.

You can use Redux together with , or with any other view library. It is tiny (2kB, including dependencies), but has a large ecosystem of addons available.

Redux is available as a package on NPM for use with a module bundler or in a Node application:

It is also available as a precompiled UMD package that defines a global variable. The UMD package can be used as a <script> tag directly.

For more details, see the page.

Redux Starter Kit

Redux itself is small and unopinionated. We also have a separate package called ,which includes some opinionated defaults that help you use Redux more effectively.

It helps simplify a lot of common use cases, including store setup,,and even creating entire "slices" of state at once.

The whole state of your app is stored in an object tree inside a single store.The only way to change the state tree is to emit an action, an object describing what happened.To specify how the actions transform the state tree, you write pure reducers.

That's it!

import { createStore } from 'redux'
/**
 * This is a reducer, a pure function with (state, action) => state signature.
 * It describes how an action transforms the state into the next state.
 *
 * The shape of the state is up to you: it can be a primitive, an array, an object,
 * or even an Immutable.js data structure. The only important part is that you should
 * not mutate the state object, but return a new object if the state changes.
 *
 * In this example, we use a `switch` statement and strings, but you can use a helper that
 * follows a different convention (such as function maps) if it makes sense for your
 * project.
function counter(state = 0, action) {
  switch (action.type) {
    case 'INCREMENT':
      return state + 1
    case 'DECREMENT':
    default:
      return state
  }
}
// Create a Redux store holding the state of your app.
// Its API is { subscribe, dispatch, getState }.
let store = createStore(counter)
// You can use subscribe() to update the UI in response to state changes.
// Normally you'd use a view binding library (e.g. React Redux) rather than subscribe() directly.
// However it can also be handy to persist the current state in the localStorage.
store.subscribe(() => console.log(store.getState()))
// The only way to mutate the internal state is to dispatch an action.
// The actions can be serialized, logged or stored and later replayed.
store.dispatch({ type: 'INCREMENT' })
// 1
store.dispatch({ type: 'INCREMENT' })
// 2
store.dispatch({ type: 'DECREMENT' })
// 1

Instead of mutating the state directly, you specify the mutations you want to happen with plain objects called actions. Then you write a special function called a reducer to decide how every action transforms the entire application's state.

In a typical Redux app, there is just a single store with a single root reducing function. As your app grows, you split the root reducer into smaller reducers independently operating on the different parts of the state tree. This is exactly like how there is just one root component in a React app, but it is composed out of many small components.

This architecture might seem like an overkill for a counter app, but the beauty of this pattern is how well it scales to large and complex apps. It also enables very powerful developer tools, because it is possible to trace every mutation to the action that caused it. You can record user sessions and reproduce them just by replaying every action.

Examples

The Redux repository contains several example projects demonstrating various aspects of how to use Redux. Almost all examples have a corresponding CodeSandbox sandbox. This is an interactive version of the code that you can play with online.

We have a variety of resources available to help you learn Redux, no matter what your background or learning style is.

The behind building Redux, the Core Concepts, and the .
The basic tutorial in the Redux docs
Redux creator Dan Abramov's free on Egghead.io
Redux co-maintainer Mark Erikson's "Redux Fundamentals" slideshow and
If you learn best by looking at code and playing with it, check out our list of Redux example applications, available as separate projects in the Redux repo, and also as interactive online examples on CodeSandbox.
The section of the React/Redux links list. Here's a top list of our recommended tutorials:
- Dave Ceddia's posts and How Redux Works: A Counter-Example are a great intro to the basics of Redux and how to use it with React, as is this post on .
- Valentino Gagliardi's post React Redux Tutorial for Beginners: Learning Redux in 2018 is an excellent extended introduction to many aspects of using Redux.
- The CSS Tricks article covers the Redux basics well.
- This DevGuides: Introduction to Redux tutorial covers several aspects of Redux, including actions, reducers, usage with React, and middleware.

Once you've picked up the basics of working with actions, reducers, and the store, you may have questions about topics like working with asynchronous logic and AJAX requests, connecting a UI framework like React to your Redux store, and setting up an application to use Redux:

The covers working with async logic, middleware, routing.
The Redux docs "Learning Resources" page points to recommended articles on a variety of Redux-related topics.
Sophie DeBenedetto's 8-part series shows how to put together a basic CRUD app from scratch.

Going from a TodoMVC app to a real production application can be a big jump, but we've got plenty of resources to help:

Redux creator Dan Abramov's free "Building React Applications with Idiomatic Redux" video series builds on his first video series and covers topics like middleware, routing, and persistence.
The answers many common questions about how to use Redux, and the "Recipes" docs section has information on handling derived data, testing, structuring reducer logic, and reducing boilerplate.
Redux co-maintainer Mark Erikson's demonstrates real-world intermediate and advanced techniques for working with React and Redux (also available as an interactive course on Educative.io).
The has categorized articles on working with reducers and selectors, , Redux architecture and best practices, and more.
Our community has created thousands of Redux-related libraries, addons, and tools. The lists our recommendations, and there's a complete listing available in the Redux addons catalog.
If you're looking to learn from actual application codebases, the addons catalog also has a list of .

Help and Discussion

The of the Reactiflux Discord community is our official resource for all questions related to learning and using Redux. Reactiflux is a great place to hang out, ask questions, and learn - come join us!

You can also ask questions on using the #redux tag.

Redux is a valuable tool for organizing your state, but you should also consider whether it's appropriate for your situation. Don't use Redux just because someone said you should - take some time to understand the potential benefits and tradeoffs of using it.

Here are some suggestions on when it makes sense to use Redux:

You have reasonable amounts of data changing over time
You need a single source of truth for your state
You find that keeping all your state in a top-level component is no longer sufficient
Yes, these guidelines are subjective and vague, but this is for good reason. The point at which you should integrate Redux into your application is different for every user and different for every application.