What’s new in React 19

By convention, functions that use async transitions are called “Actions”.

Actions automatically manage submitting data for you:

• Pending state: Actions provide a pending state that starts at the beginning of a request and automatically resets when the final state update is committed.
• Optimistic updates: Actions support the new useOptimistic hook so you can show users instant feedback while the requests are submitting.
• Error handling: Actions provide error handling so you can display Error Boundaries when a request fails, and revert optimistic updates to their original value automatically.
• Forms: <form> elements now support passing functions to the action and formAction props. Passing functions to the action props use Actions by default and reset the form automatically after submission.