React Redux Quick Start

What You'll Learn

• How to set up and use Redux Toolkit with React Redux

Prerequisites

• Familiarity with ES6 syntax and features
• Knowledge of React terminology: JSX, State, Function Components, Props, and Hooks
• Understanding of Redux terms and concepts

Introduction

Welcome to the React Redux Quick Start tutorial! This tutorial will briefly introduce you to React Redux and teach you how to start using it correctly.

How to Read This Tutorial

This page will focus on just how to set up a Redux application with Redux Toolkit and the main APIs you'll use. For explanations of what Redux is, how it works, and full examples of how to use Redux Toolkit, see the Redux core docs tutorials.

For this tutorial, we assume that you're using Redux Toolkit and React Redux together, as that is the standard Redux usage pattern. The examples are based on a typical Create-React-App folder structure where all the application code is in a src, but the patterns can be adapted to whatever project or folder setup you're using.

The Redux+JS template for Create-React-App comes with this same project setup already configured.

Usage Summary

Install Redux Toolkit and React Redux

Add the Redux Toolkit and React Redux packages to your project:

npm install @reduxjs/toolkit react-redux

Create a Redux Store

Create a file named src/app/store.js. Import the configureStore API from Redux Toolkit. We'll start by creating an empty Redux store, and exporting it:

app/store.js

import { configureStore } from '@reduxjs/toolkit'

export default configureStore({
  reducer: {},
})

This creates a Redux store, and also automatically configure the Redux DevTools extension so that you can inspect the store while developing.

Provide the Redux Store to React

Once the store is created, we can make it available to our React components by putting a React Redux <Provider> around our application in src/index.js. Import the Redux store we just created, put a <Provider> around your <App>, and pass the store as a prop:

index.js

import React from 'react'
import ReactDOM from 'react-dom/client'
import './index.css'
import App from './App'
import store from './app/store'
import { Provider } from 'react-redux'

// As of React 18
const root = ReactDOM.createRoot(document.getElementById('root'))

root.render(
  <Provider store={store}>
    <App />
  </Provider>
)

Create a Redux State Slice

Add a new file named src/features/counter/counterSlice.js. In that file, import the createSlice API from Redux Toolkit.

Creating a slice requires a string name to identify the slice, an initial state value, and one or more reducer functions to define how the state can be updated. Once a slice is created, we can export the generated Redux action creators and the reducer function for the whole slice.

Redux requires that we write all state updates immutably, by making copies of data and updating the copies. However, Redux Toolkit's createSlice and createReducer APIs use Immer inside to allow us to write "mutating" update logic that becomes correct immutable updates.

features/counter/counterSlice.js

import { createSlice } from '@reduxjs/toolkit'

export const counterSlice = createSlice({
  name: 'counter',
  initialState: {
    value: 0,
  },
  reducers: {
    increment: (state) => {
      // Redux Toolkit allows us to write "mutating" logic in reducers. It
      // doesn't actually mutate the state because it uses the Immer library,
      // which detects changes to a "draft state" and produces a brand new
      // immutable state based off those changes.
      // Also, no return statement is required from these functions.
      state.value += 1
    },
    decrement: (state) => {
      state.value -= 1
    },
    incrementByAmount: (state, action) => {
      state.value += action.payload
    },
  },
})

// Action creators are generated for each case reducer function
export const { increment, decrement, incrementByAmount } = counterSlice.actions

export default counterSlice.reducer

Add Slice Reducers to the Store

Next, we need to import the reducer function from the counter slice and add it to our store. By defining a field inside the reducer parameter, we tell the store to use this slice reducer function to handle all updates to that state.

app/store.js

import { configureStore } from '@reduxjs/toolkit'
import counterReducer from '../features/counter/counterSlice'

export default configureStore({
  reducer: {
    counter: counterReducer,
  },
})

Use Redux State and Actions in React Components

Now we can use the React Redux hooks to let React components interact with the Redux store. We can read data from the store with useSelector, and dispatch actions using useDispatch. Create a src/features/counter/Counter.js file with a <Counter> component inside, then import that component into App.js and render it inside of <App>.

features/counter/Counter.js

import React from 'react'
import { useSelector, useDispatch } from 'react-redux'
import { decrement, increment } from './counterSlice'
import styles from './Counter.module.css'

export function Counter() {
  const count = useSelector((state) => state.counter.value)
  const dispatch = useDispatch()

  return (
    <div>
      <div>
        <button
          aria-label="Increment value"
          onClick={() => dispatch(increment())}
        >
          Increment
        </button>
        <span>{count}</span>
        <button
          aria-label="Decrement value"
          onClick={() => dispatch(decrement())}
        >
          Decrement
        </button>
      </div>
    </div>
  )
}

Now, any time you click the "Increment" and "Decrement buttons:

• The corresponding Redux action will be dispatched to the store
• The counter slice reducer will see the actions and update its state
• The <Counter> component will see the new state value from the store and re-render itself with the new data

What You've Learned

That was a brief overview of how to set up and use Redux Toolkit with React. Recapping the details:

Summary

• Create a Redux store with configureStore
  • configureStore accepts a reducer function as a named argument
  • configureStore automatically sets up the store with good default settings
• Provide the Redux store to the React application components
  • Put a React Redux <Provider> component around your <App />
  • Pass the Redux store as <Provider store={store}>
• Create a Redux "slice" reducer with createSlice
  • Call createSlice with a string name, an initial state, and named reducer functions
  • Reducer functions may "mutate" the state using Immer
  • Export the generated slice reducer and action creators
• Use the React Redux useSelector/useDispatch hooks in React components
  • Read data from the store with the useSelector hook
  • Get the dispatch function with the useDispatch hook, and dispatch actions as needed

Full Counter App Example

Here's the complete Counter application as a running CodeSandbox:

What's Next?

We recommend going through the "Redux Essentials" and "Redux Fundamentals" tutorials in the Redux core docs, which will give you a complete understanding of how Redux works, what Redux Toolkit and React Redux do, and how to use it correctly.