v2.0.0-beta.0

This beta release updates many of our TS types for improved type safety and behavior, updates entityAdapter.getSelectors() to accept a createSelector option, depends on the latest redux@5.0-beta.0 release, and includes all prior changes from the 2.0 alphas. This release has breaking changes.

npm i @reduxjs/toolkit@next

yarn add @reduxjs/toolkit@next

The 2.0 integration branch contains the docs preview for the 2.0 changes. Not all changes are documented yet, but you can see API reference pages for most of the new features here:

• RTK 2.0 beta preview documentation

Changelog

Store Configuration Tweaks and Type Safety

We've seen many cases where users passing the middleware parameter to configureStore have tried spreading the array returned by getDefaultMiddleware(), or passed an alternate plain array. This unfortunately loses the exact TS types from the individual middleware, and often causes TS problems down the road (such as dispatch being typed as Dispatch<AnyAction> and not knowing about thunks).

getDefaultMiddleware() already used an internal MiddlewareArray class, an Array subclass that had strongly typed .concat/prepend() methods to correctly capture and retain the middleware types.

We've renamed that type to Tuple, and configureStore's TS types now require that you must use Tuple if you want to pass your own array of middleware:

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

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

(Note that this has no effect if you're using RTK with plain JS, and you could still pass a plain array here.)

Similarly, the enhancers field used to accept an array directly. It now is a callback that receives a getDefaultEnhancers method, equivalent to getDefaultMiddleware():

const store = configureStore({
  reducer,
  middleware: (getDefaultMiddleware) => getDefaultMiddleware().concat(logger),
  enhancers: (getDefaultEnhancers) =>
    getDefaultEnhancers({
      autoBatch: false,
    }).concat(batchedSubscribe(debounceNotify)),
})

It too expects a Tuple return value if you're using TS.

Entity Adapter Updates

entityAdapter.getSelectors() now accepts an options object as its second argument. This allows you to pass in your own preferred createSelector method, which will be used to memoize the generated selectors. This could be useful if you want to use one of Reselect's new alternate memoizers, or some other memoization library with an equivalent signature.

createEntityAdapter now has an Id generic argument, which will be used to strongly type the item IDs anywhere those are exposed. Previously, the ID field type was always string | number. TS will now try to infer the exact type from either the .id field of your entity type, or the selectId return type. You could also fall back to passing that generic type directly.

The .entities lookup table is now defined to use a standard TS Record<Id, MyEntityType>, which assumes that each item lookup exists by default. Previously, it used a Dictionary<MyEntityType> type, which assumed the result was MyEntityType | undefined. The Dictionary type has been removed.

If you prefer to assume that the lookups might be undefined, use TypeScript's noUncheckedIndexedAccess configuration option to control that.

New UnknownAction Type

The Redux core TS types have always exported an AnyAction type, which is defined to have {type: string} and treat any other field as any. This makes it easy to write uses like console.log(action.whatever), but unfortunately does not provide any meaningful type safety.

We now export an UnknownAction type, which treats all fields other than action.type as unknown. This encourages users to write type guards that check the action object and assert its specific TS type. Inside of those checks, you can access a field with better type safety.

UnknownAction is now the default any place in the Redux and RTK source that expects an action object.

AnyAction still exists for compatibility, but has been marked as deprecated.

Note that Redux Toolkit's action creators have a .match() method that acts as a useful type guard:

if (todoAdded.match(someUnknownAction)) {
  // action is now typed as a PayloadAction<Todo>
}

Earlier Alpha Changes

Summarizing the changes from earlier alphas:

New Features

• combineSlices API with built-in support for slice reducer injection for code-splitting
• selectors field in createSlice
• Callback form of createSlice.reducers, which allows defining thunks inside createSlice
• "Dynamic middleware" middleware
• configureStore adds autoBatchEnhancer by default
• Reselect v5 runs selectors an additional time on first call in dev to check for improper memoization, and includes new optional autotrack and weakmap memoizers with different tradeoffs

Breaking Changes

• Object argument for createReducer and createSlice.extraReducers has been removed
• Packaging converted to have full ESM/CJS compatibility
• Dropped UMD build artifacts
• JS build output is now "modern" and not transpiled for IE11 compatibility
• Updated to Immer 10, and dropped the legacy ES5 compat option
• Updated Redux core dep to 5.0-beta
• actionCreator.toString() override removed (although we're reconsidering this)
• Standalone getDefaultMiddleware removed
• Other deprecated fields removed

What's Changed

• Add Id type parameter in createEntityAdapter by @Matt-Ord in #3187
• Require usage of Tuple in TS by @EskiMojo14 in #3460
• Require that enhancers is a callback by @EskiMojo14 in #3461
• fix invalid createEntityAdapter call by @EskiMojo14 in #3490
• Use Record<EntityId, T> instead of Dictionary by @EskiMojo14 in #3424
• Fix inference for reducers without actions specified by @EskiMojo14 in #3475
• Prefer UnknownAction and Action to AnyAction by @EskiMojo14 in #3363
• Allow passing a createSelector instance to adapter.getSelectors by @EskiMojo14 in #3481

Full Changelog: v2.0.0-alpha.6...v2.0.0-beta.0