React 19: What’s New?

The React team is preparing a big release that will include a number of notable changes that will transform the way web developers create applications:

React Compiler

The React Compiler is one of the most eagerly awaited aspects of React 19.This ground-breaking tool was created to solve the problem of unnecessary component re-renders, which is a frequent source of frustration for React developers. Performance of applications can be significantly increased by using the React Compiler, which updates components only when necessary, diminishing the need to manually memoise the code. the compiler will test the code against the React Rules. This will also encourage developers to use ESLint and strict mode for compatibility.

Actions

React will supports a new way of handling form submission from client to server extending beyond the server capabilities in a client only application. Developers can now manage asynchronous or synchronous form submissions with React handling all lifecycle aspects. Two new hooks, useFormStatus and useFormState, are introduced to support this functionality.
1. useFormStatus : Provides submission status, action, method, and data details, making it particularly useful for managing multiple form submissions.

import { useFormStatus } from "react-dom";
import action from "./actions";
function Submit() {
 const status = useFormStatus();
 return <button disabled={status.pending}>Submit</button>;
}
export default function App() {
 return (
 <form action={action}>
 <Submit />
 </form>
 );
}

2. useFormState: Allows updating the state based on the result of the form action. It's helpful for managing form state updates.

import { useFormState } from "react-dom";
async function onIncrement(prevState, formData) {
  return prevState + 1;
}

function StatefulForm() {
  const [state, formAction] = useFormState(onIncrement, 0);
  return (
    <form>
      {state}
      <button formAction={formAction}>Increment</button>
    </form>
  );
}

Additionally, the useOptimistic hook is introduced to manage optimistic state updates, assuming successful submission on the client and reverting if necessary. It works using regular async/await, so it works the same whether you’re using fetch on the client, or a Server Action from the server.

New Features in React Canary:

• Document MetaHead: Simplifies adding titles and meta tags to pages with the <DocumentHead> component, enhancing SEO and brand consistency across the site.

• Asset Loading: React 19 improves asset loading by starting to load pictures and files in the background while users are still on the current page. This reduces waiting time when transitioning to a new page.

Conclusion:

Revolutionary innovations like the React compiler, better asset loading, and faster form submission handling are all included in React 19. Improved user experience, faster development, and increased performance are the goals of these upgrades. More productivity and seamless user experiences are what developers can anticipate from their React apps.