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@markerikson markerikson released this Apr 9, 2019 · 32 commits to master since this release

React-Redux version 7 resolves the performance issues that were reported with version 6, and lays the groundwork for us to design and ship a public useRedux()-type Hooks API in a later 7.x release.

The major change for this release is that connect is now implemented using Hooks internally. Because of this, we now require a minimum React version of 16.8.4 or higher.

This release has undergone extensive performance benchmarking, and we're confident that it's the fastest version of React-Redux yet! We've also expanded our test suite to cover a number of additional use cases and scenarios.

npm install react-redux@latest

For discussion on the reasons for the major version change and the development process, see:

issue #1177 - React-Redux Roadmap: v6, Context, Subscriptions, and Hooks.

For discussion on the possible design of a future public hooks API, see:

issue #1179: Discussion: Potential hooks API design


This release should be public-API-compatible with version 6. The only public breaking change is the update of our React peer dependency from 16.4 to 16.8.4.

Note: connect now uses React.memo() internally, which returns a special object rather than a function. Any code that assumed React components are only functions is wrong, and has been wrong since the release of React 16.6. If you were using PropTypes to check for valid component types, you should change from PropTypes.func to PropTypes.elementType instead.

Internal Changes

Direct Component Subscriptions

In v6, we switched from individual components subscribing to the store, to having <Provider> subscribe and components read the store state from React's Context API. This worked, but unfortunately the Context API isn't as optimized for frequent updates as we'd hoped, and our usage patterns led to some folks reporting performance issues in some scenarios.

In v7, we've switched back to using direct subscriptions internally, which should improve performance considerably.

(This does result in some changes that are visible to user-facing code, in that updates dispatched in React lifecycle methods are immediately reflected in later component updates. Examples of this include components dispatching while mounting in an SSR environment. This was the behavior through v5, and is not considered part of our public API.)

Batched Updates

React has an unstable_batchedUpdates API that it uses to group together multiple updates from the same event loop tick. The React team encouraged us to use this, and we've updated our internal Redux subscription handling to leverage this API. This should also help improve performance, by cutting down on the number of distinct renders caused by a Redux store update.

connect Rewritten with Hooks

We've reimplemented our connect wrapper component to use hooks internally. While it may not be visible to you, it's nice to know we can take advantage of the latest React goodies!

Public API Changes

Return of store as a Prop

We've brought back the ability to pass a store as a prop directly to connected components. This was removed in version 6 due to internal implementation changes (components no longer subscribed to the store directly). Some users expressed concerns that working with context in unit tests was not sufficient. Since our components use direct subscriptions again, we've reimplemented this option, and that should resolve those concerns.

New batch API for Batched React Updates

React's unstable_batchedUpdate() API allows any React updates in an event loop tick to be batched together into a single render pass. React already uses this internally for its own event handler callbacks. This API is actually part of the renderer packages like ReactDOM and React Native, not the React core itself.

Since React-Redux needs to work in both ReactDOM and React Native environments, we've taken care of importing this API from the correct renderer at build time for our own use. We also now re-export this function publicly ourselves, renamed to batch(). You can use it to ensure that multiple actions dispatched outside of React only result in a single render update, like this:

import { batch } from "react-redux";

function myThunk() {
    return (dispatch, getState) => {
        // should only result in one combined re-render, not two
        batch(() => {

If you are using an alternative React renderer, like the Ink CLI renderer, that method isn't available for us to import. In that case, you will need to change your code to import from the new react-redux/es/alternate-renderers entry point instead. (Use react-redux/lib/alternate-renderers for the CJS version). That entry point exports a no-op version of batch() that just executes the callback immediately, and does not provide React batching.

In that situation, you may want to consider aliasing react-redux to one of those alternate entry points in your build tool for the best compatibility, especially if you're using any other libraries that depend on React-Redux.

Note: v7.0.1 is identical code-wise to v7.0.0 . The extra patch release was to update the React requirement listed in the README.


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