The New Features of React 19: What You Need to Know

React ⚛️is the most famous UI library in front-end development today.

For developers looking to stay ahead of the React race, understanding new React 19 features is essential.

Overview of the Features

• ⚛️React compiler
• 🗄️ Server components 🖥
• 🔄Automatic Batching📦
• 🗒️SEO Metadata
• 📈Improved Data Fetching with Suspense
• 💼 Assets Loading
• 🪝 Enhanced hooks

The Revolution of React 19 is exciting and interesting. Let’s read now!

⚛️ React Compiler ⚛️

React19 is getting a new helper called the React Compiler 💡. It's like a smart code-compiling friend that makes your code work faster without you having to do extra work. This means people who make websites can write simpler code, and the compiler will make sure it runs really well. It's like having a super-smart assistant that cleans up and organizes your room for you, so you can focus on playing and having fun with React!

🗄️ Server Components 🖥

React19 comes with the superpower “🖥Server Components.”

It's like having a smart render tool that does some of the work before you even ask for it!

React19  renders UI components on the server, separate from your client-side app or traditional server-side rendering (SSR) setup. By pre-rendering components on the server, RSCs can automatically improve page speed times.

This means when you open a website, the pictures and words show up much faster. It's especially helpful for websites with lots of cool stuff on them. The best part is that these server components can work in different ways depending on what the website needs.

Code Example: Server Components

// ServerComponent.server.js

export default function ServerComponent() {

return <div>Hello from the server!</div>;

}

// App.client.js

import React from 'react';

import { createRoot } from 'react-dom/client';

import ServerComponent from './ServerComponent.server';

function App() {

return (

<div>

<ServerComponent />

</div>

);

}

const root = createRoot(document.getElementById('root'));

root.render(<App />);

So, server components make websites load super quick which means less waiting and more speed for you!

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🔄Automatic Batching📦

React 19 introduces automatic batching for all updates inside event handlers. This means that multiple state updates inside a single event handler will now be batched automatically, leading to fewer re-renders and improved performance.

Code Example: Automatic Batching

import React, { useState } from 'react';

import { createRoot } from 'react-dom/client';

function App() {

const [count, setCount] = useState(0);

const [text, setText] = useState('');

  const handleClick = () => {

setCount(count + 1);

setText('Updated text');

};

  return (

<div>

<button onClick={handleClick}>Update</button>

<div>Count: {count}</div>

<div>Text: {text}</div>

</div>

);

}

🗒️SEO Metadata 📝

React 19 is now an AutoSEO Feature that helps websites be found on the internet! Now, React simplifies SEO-sensitive elements and you can easily control titles, descriptions, and other SEO-relevant elements directly within your React application. This way, when someone looks for something on the internet, they can find the right websites faster.

📈Improved Data Fetching With Suspense

React 19 builds on the Suspense feature to make data fetching easier and more intuitive. With the new data fetching capabilities, you can now handle asynchronous operations more gracefully within your components.

Code Example: Data Fetching with Suspense

import React, { Suspense } from 'react';

import { createRoot } from 'react-dom/client';

const fetchData = () => {

return new Promise(resolve => {

setTimeout(() => {

resolve('Data fetched from server');

}, 2000);

});

};

const DataComponent = React.lazy(async () => {

const data = await fetchData();

return {

default: () => <div>{data}</div>

};

});

function App() {

return (

<div>

<Suspense fallback={<div>Loading...</div>}>

<DataComponent />

</Suspense>

</div>

);

}

const root = createRoot(document.getElementById('root'));

root.render(<App />);

💼 Assets Loading

React 19 has a feature where Assets Loads Auto in the background so websites work faster and look better!

It starts loading pictures and other stuff for the next page while you're still looking at the current one. This means when you click to go to a new page, it shows up super fast!

Have you ever seen a website that looks weird for a split second when it first loads? Like the words are in the wrong place or the colors are all mixed up? React 19 fixes this too. It makes sure everything looks just right before showing it to you.
Code Example: Concurrent Rendering

import React, { useState, Suspense } from 'react';

import { createRoot } from 'react-dom/client';

const SlowComponent = React.lazy(() => import('./SlowComponent'));

function App() {

const [show, setShow] = useState(false);

  return (

<div>

<button onClick={() => setShow(true)}>Show Slow Component</button>

<Suspense fallback={<div>Loading...</div>}>

{show && <SlowComponent />}

</Suspense>

</div>

);

}

const root = createRoot(document.getElementById('root'));

root.render(<App />);

This way, the website can work on loading stuff in the background without bothering you while you're using it. Focus on what matters.

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Hooks

React 19 introduces new hooks to help manage events and optimistic UI updates more effectively. The useEvent hook provides a simpler way to handle event listeners, while the useOptimistic hook helps manage optimistic UI states.

Code Example: useEvent Hook

import React, { useEvent } from 'react';

import { createRoot } from 'react-dom/client';

function App() {

const handleClick = useEvent(() => {

console.log('Button clicked!');

});

  return (

<div>

<button onClick={handleClick}>Click Me</button>

</div>

);

}

const root = createRoot(document.getElementById('root'));

root.render(<App />);

Code Example: useOptimistic Hook

import React, { useOptimistic } from 'react';

import { createRoot } from 'react-dom/client';

function App() {

const [optimisticState, setOptimisticState] = useOptimistic(0);

  const handleClick = () => {

setOptimisticState((prevState) => prevState + 1);

};

  return (

<div>

<button onClick={handleClick}>Increment</button>

<div>Optimistic Count: {optimisticState}</div>

</div>

);

}

const root = createRoot(document.getElementById('root'));

root.render(<App />);

🌟 Summary “ Don't Miss Out! “

We talked about many things in this article.

Let's quickly go over the cool new stuff coming in the next version of React 19.

React 19 brings a host of new features and improvements that make building responsive, efficient, and scalable applications easier than ever. From concurrent rendering enhancements to new hooks like useEvent and useOptimistic, these updates provide powerful tools for React developers. Experiment with these new features in your projects, and take advantage of the latest advancements in the React ecosystem.

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Stay tuned for more updates, and happy </> coding!

Previously published at https://blog.wrappixel.com/react-19-whats-new-features/