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configureStore

The standard method for creating a Redux store. It uses the low-level Redux core createStore method internally, but wraps that to provide good defaults to the store setup for a better development experience.

Purpose and Behavior​

A standard Redux store setup typically requires multiple pieces of configuration:

  • Combining the slice reducers into the root reducer
  • Creating the middleware enhancer, usually with the thunk middleware or other side effects middleware, as well as middleware that might be used for development checks
  • Adding the Redux DevTools enhancer, and composing the enhancers together
  • Calling createStore

Legacy Redux usage patterns typically required several dozen lines of copy-pasted boilerplate to achieve this.

Redux Toolkit's configureStore simplifies that setup process, by doing all that work for you. One call to configureStore will:

  • Call combineReducers to combine your slices reducers into the root reducer function
  • Add the thunk middleware and called applyMiddleware
  • In development, automatically add more middleware to check for common mistakes like accidentally mutating the state
  • Automatically set up the Redux DevTools Extension connection
  • Call createStore to create a Redux store using that root reducer and those configuration options

configureStore also offers an improved API and usage patterns compared to the original createStore by accepting named fields for reducer, preloadedState, middleware, enhancers, and devtools, as well as much better TS type inference.

Parameters​

configureStore accepts a single configuration object parameter, with the following options:


interface ConfigureStoreOptions<
  S = any,
  A extends Action = UnknownAction,
  M extends Tuple<Middlewares<S>> = Tuple<Middlewares<S>>
  E extends Tuple<Enhancers> = Tuple<Enhancers>,
  P = S
> {
  /**
   * A single reducer function that will be used as the root reducer, or an
   * object of slice reducers that will be passed to `combineReducers()`.
   */
  reducer: Reducer<S, A, P> | ReducersMapObject<S, A, P>

  /**
   * An array of Redux middleware to install. If not supplied, defaults to
   * the set of middleware returned by `getDefaultMiddleware()`.
   */
  middleware?: ((getDefaultMiddleware: CurriedGetDefaultMiddleware<S>) => M) | M

  /**
   * Whether to enable Redux DevTools integration. Defaults to `true`.
   *
   * Additional configuration can be done by passing Redux DevTools options
   */
  devTools?: boolean | DevToolsOptions

  /**
   * The initial state, same as Redux's createStore.
   * You may optionally specify it to hydrate the state
   * from the server in universal apps, or to restore a previously serialized
   * user session. If you use `combineReducers()` to produce the root reducer
   * function (either directly or indirectly by passing an object as `reducer`),
   * this must be an object with the same shape as the reducer map keys.
   */
  preloadedState?: P

  /**
   * The store enhancers to apply. See Redux's `createStore()`.
   * All enhancers will be included before the DevTools Extension enhancer.
   * If you need to customize the order of enhancers, supply a callback
   * function that will receive the getDefaultEnhancers,
   * and should return a new array (such as `getDefaultEnhancers().concat(offline)`).
   * If you only need to add middleware, you can use the `middleware` parameter instead.
   */
  enhancers?: (getDefaultEnhancers: GetDefaultEnhancers<M>) => E | E
}

function configureStore<
  S = any,
  A extends Action = UnknownAction,
  M extends Tuple<Middlewares<S>> = Tuple<Middlewares<S>>
  E extends Tuple<Enhancers> = Tuple<Enhancers>,
  P = S
>(options: ConfigureStoreOptions<S, A, M, E, P>): EnhancedStore<S, A, M, E>

reducer​

If this is a single function, it will be directly used as the root reducer for the store.

If it is an object of slice reducers, like {users : usersReducer, posts : postsReducer}, configureStore will automatically create the root reducer by passing this object to the Redux combineReducers utility.

middleware​

A callback which will receive getDefaultMiddleware as its argument, and should return a middleware array.

If this option is provided, it should return all the middleware functions you want added to the store. configureStore will automatically pass those to applyMiddleware.

If not provided, configureStore will call getDefaultMiddleware and use the array of middleware functions it returns.

For more details on how the middleware parameter works and the list of middleware that are added by default, see the getDefaultMiddleware docs page.

Tuple

Typescript users are required to use a Tuple instance (if not using a getDefaultMiddleware result, which is already a Tuple), for better inference.

import { configureStore, Tuple } from '@reduxjs/toolkit'

configureStore({
  reducer: rootReducer,
  middleware: () => new Tuple(additionalMiddleware, logger),
})

Javascript-only users are free to use a plain array if preferred.

devTools​

If this is a boolean, it will be used to indicate whether configureStore should automatically enable support for the Redux DevTools browser extension.

If it is an object, then the DevTools Extension will be enabled, and the options object will be passed to composeWithDevtools(). See the DevTools Extension docs for EnhancerOptions for a list of the specific options that are available.

Defaults to true.

trace​

The Redux DevTools Extension recently added support for showing action stack traces that show exactly where each action was dispatched. Capturing the traces can add a bit of overhead, so the DevTools Extension allows users to configure whether action stack traces are captured by setting the 'trace' argument. If the DevTools are enabled by passing true or an object, then configureStore will default to enabling capturing action stack traces in development mode only.

preloadedState​

An optional initial state value to be passed to the Redux createStore function.

enhancers​

A callback function to customize the array of enhancers.

Enhancers returned by this callback will be passed to the Redux compose function, and the combined enhancer will be passed to createStore.

Dev Tools

This should not include the Redux DevTools Extension composeWithDevTools, as this is already handled by configureStore.

Example: enhancers: () => new Tuple(offline) will result in a final setup of [offline, devToolsExtension].

If not provided, configureStore will call getDefaultEnhancers and use the array of enhancers it returns (including applyMiddleware with specified middleware).

Where you wish to add onto or customize the default enhancers, you may pass a callback function that will receive getDefaultEnhancers as its argument, and should return an enhancer array.

Example: enhancers: (defaultEnhancers) => defaultEnhancers.prepend(offline) will result in a final setup of [offline, applyMiddleware, devToolsExtension].

For more details on how the enhancer parameter works and the list of enhancers that are added by default, see the getDefaultEnhancers docs page.

Middleware

If you don't use getDefaultEnhancers and instead return an array, the applyMiddleware enhancer will not be used.

configureStore will warn in console if any middleware are provided (or left as default) but not included in the final list of enhancers.

// warns - middleware customised but not included in final enhancers
configureStore({
  reducer,
  middleware: (getDefaultMiddleware) => getDefaultMiddleware().concat(logger)
  enhancers: [offline(offlineConfig)],
})

// fine - default enhancers included
configureStore({
  reducer,
  enhancers: (getDefaultEnhancers) => getDefaultEnhancers().concat(offline(offlineConfig)),
})

// also allowed
configureStore({
  reducer,
  middleware: () => [],
  enhancers: () => [offline(offlineConfig)],
})

Note that if using Typescript, the middleware option is required to be provided before the enhancer option, as the type of getDefaultEnhancers depends on its result.

Tuple

Typescript users are required to use a Tuple instance (if not using a getDefaultEnhancer result, which is already a Tuple), for better inference.

import { configureStore, Tuple } from '@reduxjs/toolkit'

configureStore({
  reducer: rootReducer,
  enhancers: () => new Tuple(offline),
})

Javascript-only users are free to use a plain array if preferred.

Usage​

Basic Example​

import { configureStore } from '@reduxjs/toolkit'

import rootReducer from './reducers'

const store = configureStore({ reducer: rootReducer })
// The store now has redux-thunk added and the Redux DevTools Extension is turned on

Full Example​

// file: todos/todosReducer.ts noEmit
import type { Reducer } from '@reduxjs/toolkit'
declare const reducer: Reducer<{}>
export default reducer

// file: visibility/visibilityReducer.ts noEmit
import type { Reducer } from '@reduxjs/toolkit'
declare const reducer: Reducer<{}>
export default reducer

// file: store.ts
import { configureStore } from '@reduxjs/toolkit'

// We'll use redux-logger just as an example of adding another middleware
import logger from 'redux-logger'

// And use redux-batched-subscribe as an example of adding enhancers
import { batchedSubscribe } from 'redux-batched-subscribe'

import todosReducer from './todos/todosReducer'
import visibilityReducer from './visibility/visibilityReducer'

const reducer = {
  todos: todosReducer,
  visibility: visibilityReducer,
}

const preloadedState = {
  todos: [
    {
      text: 'Eat food',
      completed: true,
    },
    {
      text: 'Exercise',
      completed: false,
    },
  ],
  visibilityFilter: 'SHOW_COMPLETED',
}

const debounceNotify = _.debounce((notify) => notify())

const store = configureStore({
  reducer,
  middleware: (getDefaultMiddleware) => getDefaultMiddleware().concat(logger),
  devTools: process.env.NODE_ENV !== 'production',
  preloadedState,
  enhancers: (getDefaultEnhancers) =>
    getDefaultEnhancers({
      autoBatch: false,
    }).concat(batchedSubscribe(debounceNotify)),
})

// The store has been created with these options:
// - The slice reducers were automatically passed to combineReducers()
// - redux-thunk and redux-logger were added as middleware
// - The Redux DevTools Extension is disabled for production
// - The middleware, batched subscribe, and devtools enhancers were composed together
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