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Redux Toolkit Quick Start

What You'll Learn
  • How to set up and use Redux Toolkit with React-Redux
Prerequisites

Introduction​

Welcome to the Redux Toolkit Quick Start tutorial! This tutorial will briefly introduce you to Redux Toolkit 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 tutorials linked in the "Tutorials Overview" page.

For this tutorial, we assume that you're using Redux Toolkit with React, but you can also use it with other UI layers as well. 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 const store = configureStore({
  reducer: {},
})

// Infer the `RootState` and `AppDispatch` types from the store itself
export type RootState = ReturnType<typeof store.getState>
// Inferred type: {posts: PostsState, comments: CommentsState, users: UsersState}
export type AppDispatch = typeof store.dispatch

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

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById('root')
)

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'
import type { PayloadAction } from '@reduxjs/toolkit'

export interface CounterState {
  value: number
}

const initialState: CounterState = {
  value: 0,
}

export const counterSlice = createSlice({
  name: 'counter',
  initialState,
  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
      state.value += 1
    },
    decrement: (state) => {
      state.value -= 1
    },
    incrementByAmount: (state, action: PayloadAction<number>) => {
      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 const store = configureStore({
  reducer: {
    counter: counterReducer,
  },
})

// Infer the `RootState` and `AppDispatch` types from the store itself
export type RootState = ReturnType<typeof store.getState>
// Inferred type: {posts: PostsState, comments: CommentsState, users: UsersState}
export type AppDispatch = typeof store.dispatch

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 type { RootState } from '../../app/store'
import { useSelector, useDispatch } from 'react-redux'
import { decrement, increment } from './counterSlice'

export function Counter() {
  const count = useSelector((state: RootState) => 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​

The counter example app shown here is also the

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 does, and how to use it correctly.

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