1. React Compiler

The highlight of the show is the React's very own new compiler that according to the team is currently powering Instagram in production. This compiler aims to optimize React applications by automatically re-rendering only the necessary parts of the UI when state changes.

What does this mean, you won't need to use the useMemo or useCallback hook ever again instead it will be taken care of by the compiler itself meaning automatic memoization along with some javascript optimizations which we manually needed to do before as manual memoization is a compromise. It clutters up our code, is easy to get wrong, and requires extra work to keep up to date.

You can see the new compiler in action{" "} here which the team showcased in last fall.

2. Actions

Introducing Actions, a new feature in React for managing data submission from the client to the server. With Actions, developers can define functions to handle synchronous or asynchronous data operations, simplifying form handling and database mutations.

Designed to streamline data submission and manipulation, developers can now effortlessly define and manage both synchronous and asynchronous data operations, simplifying form handling and database interactions.

With Actions, React empowers developers to create dynamic and responsive user interfaces, enhancing the overall user experience. Whether handling form submissions or executing database mutations, Actions provide a seamless and intuitive way to manage data flow in React applications.

The action function operates both synchronously and asynchronously. Whether defined on the client side with standard JavaScript or on the server using the 'use server' directive, React manages data submission's lifecycle. It offers hooks like useFormStatus and useFormState to access form action's current state and response effortlessly. Actions are now available in the Canary channel and will ship in the next release of React.

3. New useOptimistic hook

useOptimistic feature enables developers to apply temporary updates that automatically revert once the final state commits. For Actions, useOptimistic allows you to optimistically set the final state of data on the client, assuming successful submission, and then revert to the server-received data. Utilizing standard async/await functionality, useOptimistic seamlessly integrates with both client-side fetch operations and server-side Actions, ensuring consistent behavior across environments.

For instance, in a chat application, sending a message triggers an optimistic update, instantly displaying the message in the chat window. This enhances user experience by providing real-time feedback while the message is being sent to the server. In case of network delays or errors, the UI gracefully handles the situation, ensuring a smooth user interaction.

4. New Features in React Canary

React Canary now includes several exciting features such as React Server Components, Asset Loading, Document Metadata, Directives, and Actions. These enhancements provide greater control and efficiency in building React applications across different environments.

Directives:

React introduces "use client" and "use server" directives, marking the division between client and server environments. "use client" generates a <script> tag for client-side interactivity, while "use server" creates a POST endpoint (like tRPC Mutations) for server-side logic. These directives enable seamless integration of client and server functionality in reusable components.

Document Metadata:

With built-in support for rendering <title>, <meta>, and metadata <link> tags, React simplifies document metadata management. This feature works across various environments, including client-side code, SSR, and RSC. It mirrors functionalities of libraries like React Helmet, enhancing document management within React applications.

Asset Loading:

Suspense integration enhances React's asset loading capabilities, allowing precise determination of content readiness. New Resource Loading APIs like preload and preinit offer finer control over resource loading and initialization. These improvements optimize performance and user experience in React applications.

Suspense is now seamlessly integrated with the loading lifecycle of various resources like stylesheets, fonts, and scripts. This allows React to accurately determine content readiness within elements such as <style>, <link>, and <script>. Additionally, to enhance control over resource loading and initialization, we've introduced new Resource Loading APIs like preload and preinit.

5. The Next Major Version of React

Get ready for React 19! This major version will include groundbreaking improvements like support for Web Components, making React even more versatile and powerful for developers.

6. Offscreen (renamed to Activity)

Previously known as Offscreen, the Activity feature is undergoing research to refine its functionality and working towards creating a more dynamic and responsive user experience. Stay tuned for more updates!

You can read more about React 19 here!

Conclusion

The new React 19's update introduces compelling features such as the compiler and server actions, which have the potential to streamline development processes. This may impact the relevance of additional frameworks like NextJS. As React 19 continues to evolve, we remain committed to providing thorough coverage and insights. Keep abreast of our updates as we delve deeper into more React 19's features.

For professional assistance in creating modern web applications that are based on React 19 latest features do consider connecting with einfonets. einfonets specializes in creating modern day web applications that are up to date with the latest trends.