React 18 brings a host of new features and improvements aimed at enhancing performance and providing developers with more robust tools for building modern web applications. In this article, we’ll delve into some of the most exciting new features of React 18, complete with examples and practical usage tips.

Concurrent Rendering

One of the most anticipated features in React 18 is concurrent rendering. This allows React to work on multiple tasks at the same time, improving the responsiveness and fluidity of applications.

Example: Using Concurrent Rendering

To enable concurrent rendering, you’ll need to use the new createRoot API instead of the traditional ReactDOM.render.

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

const container = document.getElementById('root');
const root = createRoot(container); // Create a root.
root.render(<App tab="home" />);

This approach allows React to pause, interrupt, and resume rendering work as needed, leading to smoother user experiences, especially in complex applications.

Automatic Batching

React 18 introduces automatic batching, which groups multiple state updates into a single re-render for better performance. Previously, batching was limited to React event handlers, but now it works across asynchronous contexts like timeouts, promises, and more.

Example: Automatic Batching in Action

Consider the following example where multiple state updates are batched together:

import { useState } from 'react';

function Counter() {
  const [count, setCount] = useState(0);
  const [text, setText] = useState('');

  function handleClick() {
    setCount(c => c + 1);
    setText('Clicked');
  }

  return (
    <div>
      <button onClick={handleClick}>Click me</button>
      <p>{count}</p>
      <p>{text}</p>
    </div>
  );
}

In this scenario, clicking the button triggers both setCount and setText updates, which are automatically batched, resulting in a single re-render instead of two.

Suspense for Data Fetching

Suspense is not new, but React 18 extends its capabilities to handle asynchronous data fetching, making it easier to manage loading states in your application.

Example: Suspense for Data Fetching

Here’s how you can use Suspense with React 18 to fetch data:

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

const fetchData = () => {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve("Data fetched!");
    }, 2000);
  });
};

const DataComponent = () => {
  const [data, setData] = useState(null);

  useEffect(() => {
    fetchData().then(result => setData(result));
  }, []);

  if (!data) {
    throw new Promise(resolve => setTimeout(resolve, 1000));
  }

  return <div>{data}</div>;
};

function App() {
  return (
    <Suspense fallback={<div>Loading...</div>}>
      <DataComponent />
    </Suspense>
  );
}

export default App;

In this example, DataComponent fetches data and leverages Suspense to display a fallback UI (“Loading…”) while waiting for the data to load.

Transition API

The new Transition API helps in managing UI transitions by allowing React to distinguish between urgent and non-urgent updates. This can be particularly useful for creating smooth transitions and animations.

Example: Using the Transition API

import { useState, startTransition } from 'react';

function App() {
  const [count, setCount] = useState(0);
  const [text, setText] = useState('');

  function handleClick() {
    startTransition(() => {
      setCount(c => c + 1);
    });
    setText('Clicked');
  }

  return (
    <div>
      <button onClick={handleClick}>Click me</button>
      <p>{count}</p>
      <p>{text}</p>
    </div>
  );
}

export default App;

Here, the startTransition the function allows React to prioritize the setText update over the setCount update, ensuring a smoother user experience.

React 18 introduces several powerful features designed to improve performance and developer experience. Concurrent rendering, automatic batching, Suspense for data fetching, and the Transition API are just a few highlights that can significantly enhance your React applications.

By incorporating these features, developers can create more responsive, efficient, and user-friendly web applications.

Explore these features in your projects to take full advantage of what React 18 has to offer. Happy coding!