v8.0.0
This major version release updates useSelector
, connect
, and <Provider>
for compatibility with React 18, rewrites the React-Redux codebase to TypeScript (obsoleting use of @types/react-redux
), modernizes build output, and removes the deprecated connectAdvanced
API and the pure
option for connect
.
npm i react-redux@latest
yarn add react-redux@latest
Overview, Compatibility, and Migration
Our public API is still the same ( <Provider>
, connect
and useSelector/useDispatch
), but we've updated the internals to use the new useSyncExternalStore
hook from React. React-Redux v8 is still compatible with all versions of React that have hooks (16.8+, 17.x, and 18.x; React Native 0.59+), and should just work out of the box.
In most cases, it's very likely that the only change you will need to make is bumping the package version to "react-redux": "^8.0"
.
If you are using the rarely-used connectAdvanced
API, you will need to rewrite your code to avoid that, likely by using the hooks API instead. Similarly, the pure
option for connect
has been removed.
If you are using Typescript, React-Redux is now written in TS and includes its own types. You should remove any dependencies on @types/react-redux
.
While not directly tied to React-Redux, note that the recently updated @types/react@18
major version has changed component definitions to remove having children
as a prop by default. This causes errors if you have multiple copies of @types/react
in your project. To fix this, tell your package manager to resolve @types/react
to a single version. Details:
React issue #24304: React 18 types broken since release
Additionally, please see the React post on How to Ugprade to React 18 for details on how to migrate existing apps to correctly use React 18 and take advantage of its new features.
Changelog
React 18 Compatibility
React-Redux now requires the new useSyncExternalStore
API in React 18. By default, it uses the "shim" package which backfills that API in earlier React versions, so React-Redux v8 is compatible with all React versions that have hooks (16.8+, and React Native 0.59+) as its acceptable peer dependencies.
We'd especially like to thank the React team for their extensive support and cooperation during the useSyncExternalStore
development effort. They specifically designed useSyncExternalStore
to support the needs and use cases of React-Redux, and we used React-Redux v8 as a testbed for how useSyncExternalStore
would behave and what it needed to cover. This in turn helped ensure that useSyncExternalStore
would be useful and work correctly for other libraries in the ecosystem as well.
Our performance benchmarks show parity with React-Redux v7.2.5 for both connect
and useSelector
, so we do not anticipate any meaningful performance regressions.
useSyncExternalStore
and Bundling
The useSyncExternalStore
shim is imported directly in the main entry point, so it's always included in bundles even if you're using React 18. This adds roughly 600 bytes minified to your bundle size.
If you are using React 18 and would like to avoid that extra bundle cost, React-Redux now has a new /next
entry point. This exports the exact same APIs, but directly imports useSyncExternalStore
from React itself, and thus avoids including the shim. You can alias "react-redux": "react-redux/next"
in your bundler to use that instead.
SSR and Hydration
React 18 introduces a new hydrateRoot
method for hydrating the UI on the client in Server-Side Rendering usage. As part of that, the useSyncExternalStore
API requires that we pass in an alternate state value other than what's in the actual Redux store, and that alternate value will be used for the entire initial hydration render to ensure the initial rehydrated UI is an exact match for what was rendered on the server. After the hydration render is complete, React will then apply any additional changes from the store state in a follow-up render.
React-Redux v8 supports this by adding a new serverState
prop for <Provider>
. If you're using SSR, you should pass your serialized state to <Provider>
to ensure there are no hydration mismatch errors:
import { hydrateRoot } from 'react-dom/client'
import { configureStore } from '@reduxjs/toolkit'
import { Provider } from 'react-redux'
const preloadedState = window.__PRELOADED_STATE__
const clientStore = configureStore({
reducer: rootReducer,
preloadedState,
})
hydrateRoot(
document.getElementById('root'),
<Provider store={clientStore} serverState={preloadedState}>
<App />
</Provider>
)
TypeScript Migration and Support
The React-Redux library source has always been written in plain JS, and the community maintained the TS typings separately as @types/react-redux
.
We've (finally!) migrated the React-Redux codebase to TypeScript, using the existing typings as a starting point. This means that the @types/react-redux
package is no longer needed, and you should remove that as a dependency.
Note Please ensure that any installed copies of
redux
and@types/react
are de-duped. You are also encouraged to update to the latest versions of Redux Toolkit (1.8.1+) or Redux (4.1.2), to ensure consistency between installed types and avoid problems from types mismatches.
We've tried to maintain the same external type signatures as much as possible. If you do see any compile problems, please file issues with any apparent TS-related problems so we can review them.
The TS migration was a great collaborative effort, with many community members contributing migrated files. Thank you to everyone who helped out!
In addition to the "pre-typed" TypedUseSelectorHook
, there's now also a Connect<State = unknown>
type that can be used as a "pre-typed" version of connect
as well.
As part of the process, we also updated the repo to use Yarn 3, copied the typetests files from DefinitelyTyped and expanded them, and improved our CI setup to test against multiple TS versions.
Removal of the DefaultRootState
type
The @types/react-redux
package, which has always been maintained by the community, included a DefaultRootState
interface that was intended for use with TS's "module augmentation" capability. Both connect
and useSelector
used this as a fallback if no state generic was provided. When we migrated React-Redux to TS, we copied over all of the types from that package as a starting point.
However, the Redux team specifically considers use of a globally augmented state type to be an anti-pattern. Instead, we direct users to extract the RootState
and AppDispatch
types from the store setup, and create pre-typed versions of the React-Redux hooks for use in the app.
Now that React-Redux itself is written in TS, we've opted to remove the DefaultRootState
type entirely. State generics now default to unknown
instead.
Technically the module augmentation approach can still be done in userland, but we discourage this practice.
Modernized Build Output
We've always targeted ES5 syntax in our published build artifacts as the lowest common denominator. Even the "ES module" artifacts with import/export
keywords still were compiled to ES5 syntax otherwise.
With IE11 now effectively dead and many sites no longer supporting it, we've updated our build tooling to target a more modern syntax equivalent to ES2017, which shrinks the bundle size slightly.
If you still need to support ES5-only environments, please compile your own dependencies as needed for your target environment.
Removal of Legacy APIs
We announced in 2019 that the legacy connectAdvanced
API would be removed in the next major version, as it was rarely used, added internal complexity, and was also basically irrelevant with the introduction of hooks. As promised, we've removed that API.
We've also removed the pure
option for connect
, which forced components to re-render regardless of whether props/state had actually changed if it was set to false
. This option was needed in some cases in the early days of the React ecosystem, when components sometimes relied on external mutable data sources that could change outside of rendering. Today, no one writes components that way, the option was barely used, and React 18's useSyncExternalStore
strictly requires immutable updates. So, we've removed the pure
flag.
Given that both of these options were almost never used, this shouldn't meaningfully affect anyone.
Changes
Due to the TS migration effort and number of contributors, this list covers just the major changes:
- Integrate TypeScript port by @markerikson in #1739
- Initial experimental React 18 compat prototyping by @markerikson in #1808
- Fix compatibility with React 18 strict effects by @markerikson in #1817
- Update to latest React 18 alpha dependencies by @markerikson in #1834
- Port remaining v7 typetests and improve v8 types by @markerikson in #1855
- Add initial SSR support for React 18 and React-Redux v8 by @markerikson in #1835
- test: Adjust type tests to be compatible with React 18 typings by @eps1lon in #1868
- Switch back to Subscription in useSelector to fix unsubscribe perf by @markerikson in #1870
- Cleanup more code after
pure
removal by @Andarist in #1859 - Swap
useSyncExternalStore
shim behavior and update React deps by @markerikson in #1884 - Remove
DefaultRootState
type by @markerikson in #1887 - Add SSR test for
serverState
behavior by @markerikson in #1888 - Cleanup internal types in selectorFactory.ts by @Methuselah96 in #1889
- Remove ts-ignore for initMergeProps by @Methuselah96 in #1891
- fix(deps): add optional peer deps into
peerDependencies
by @kyletsang in #1893 - Update peer deps for v8 by @markerikson in #1895
- Port DT fix for
dispatchProp
arg inmergeProps
by @markerikson in #1897 - Update docs for v8 final by @markerikson in #1902