TL;DR

Server Actions (a new way to handle form submissions) now correctly include all FormData entries, resolving a recent regression across multiple React versions.

Fixes Worth Knowing

Server Actions now reliably pass all form data, addressing an issue where some entries were missing after submissions.

TL;DR

React Hooks now supports ESLint v10, delivering performance improvements and more accurate linting, particularly for useEffect and ref validation.

New

• ESLint v10 support has been added. (Code analysis tool)
• Performance is improved by skipping compilation for files that don’t use React.

Fixes Worth Knowing

• useEffect validation is more accurate, reducing false positives.
• Ref validation is improved for event handlers and non-mutating functions.
• The linter now reports all errors, instead of stopping after the first one.
• Error messages are more informative with improved source locations.
• A previously removed rule, component-hook-factories, has been restored for compatibility.

TL;DR

React Hooks linting is stricter: component names must begin with a capital letter, preventing issues with hooks called in incorrectly named functions.

Breaking

• Component names must start with an uppercase letter (React Hooks).
• useEvent has been renamed to useEffectEvent (React Hooks).

New

• ESLint v9 is now supported (ESLint integration).
• use() is now fully supported and no longer experimental (React Hooks).

Fixes Worth Knowing

• Hooks can now be used within useEffect dependencies, and async functions are correctly flagged for improper hook usage (React Hooks).

Before You Upgrade

• Update any component names starting with a lowercase or underscore to use a capital letter.
• Replace all instances of useEvent with useEffectEvent in your code.

TL;DR

React now issues warnings for many deprecated features, preparing developers for the larger changes coming in React 19.

Breaking

• Deprecated APIs will now show warnings (informational messages indicating features to avoid).

New

• act is now exported directly from the react package (utility for controlling state updates).

Fixes Worth Knowing

• String refs can now be used with this.refs (older method of accessing components).

Before You Upgrade

• Review the React 19 Upgrade Guide to understand upcoming changes and address any warnings in your codebase.

TL;DR

React 17 improves stability and addresses a potential browser warning, ensuring continued compatibility and a smoother experience for users on older browsers like IE11.

Breaking

None

New

None

Fixes Worth Knowing

• Fixed a crash in Internet Explorer 11.
• Removed an unused dependency resolving a SharedArrayBuffer warning (browser security feature) in Chrome and other browsers.

Before You Upgrade

No action is needed.

TL;DR

React now supports a new JSX transform that removes the need to import React in JSX files, simplifying component code.

New

• New JSX Transform: Components no longer require React imports when using JSX (a syntax extension to JavaScript).

Before You Upgrade

• Update your build configuration to use the new JSX transform; consult the React blog post for details (https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html).

TL;DR

React now supports the new JSX Transform, enabling a more concise syntax and removing the need to import React in JSX files.

New

• New JSX Transform: Allows omitting React imports in JSX (JavaScript XML - React's syntax extension) and simplifies JSX code.

Before You Upgrade

• Update your build tooling (Babel, webpack, etc.) to support the new JSX transform; consult your tooling's documentation for instructions.

TL;DR

React 15.x now supports the new JSX Transform, offering improved performance and developer experience with modern build tools (like Babel or SWC).

New

• New JSX Transform Support: Enables use of the latest JSX features without upgrading to React 16+ (requires compatible build tooling).

Before You Upgrade

• Update your build configuration (Babel, SWC, etc.) to utilize the new JSX transform; consult the React blog post for details (https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html).

TL;DR

React now provides Universal Module Definition (UMD) builds, improving compatibility with a wider range of environments and build tools.

Breaking

• No breaking changes in this release.

New

• UMD builds are now available via unpkg, simplifying integration with older browsers and systems that don’t fully support ES modules (JavaScript modules).

Fixes Worth Knowing

• No fixes worth knowing in this release.

Before You Upgrade

• No action needed.

No release notes content available to summarize.