The Future of React: What’s New in React 18
React continues to be one of the most popular libraries for building user interfaces, and its development is ongoing. With the release of React 18, a new set of features and improvements are being introduced that aim to make React even more powerful and efficient.
M Zeeshan
8/16/20243 min read
1. Concurrent Rendering
One of the most significant updates in React 18 is the introduction of Concurrent Rendering. This feature allows React to prepare multiple versions of the UI at the same time, making the UI more responsive by prioritizing urgent updates over less critical ones.
Key Benefits:
Improved User Experience: By allowing React to interrupt rendering tasks and prioritize the most important updates, the UI remains smooth and responsive, even during heavy computations.
Automatic Batching: React 18 introduces automatic batching of updates, which reduces the number of renders and improves performance.
Example:
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import { useState } from 'react'; function App() { const [text, setText] = useState(''); const [items, setItems] = useState([]); const handleChange = (e) => { setText(e.target.value); // Simulate an expensive operation setItems(Array(10000).fill(e.target.value)); }; return ( <div> <input type="text" value={text} onChange={handleChange} /> <ul> {items.map((item, index) => ( <li key={index}>{item}</li> ))} </ul> </div> ); }
In this example, React 18’s concurrent rendering would ensure that the text input remains responsive even as the list of items is updated, preventing the UI from becoming unresponsive during heavy updates.
2. Transition API
React 18 introduces a new Transition API that allows developers to mark certain updates as non-urgent, giving React more control over how updates are prioritized. This is particularly useful for updates that don't need to be reflected in the UI immediately, like loading states or background updates.
Example:
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import { useState, startTransition } from 'react'; function App() { const [text, setText] = useState(''); const [items, setItems] = useState([]); const handleChange = (e) => { const value = e.target.value; setText(value); startTransition(() => { setItems(Array(10000).fill(value)); }); }; return ( <div> <input type="text" value={text} onChange={handleChange} /> <ul> {items.map((item, index) => ( <li key={index}>{item}</li> ))} </ul> </div> ); }
In this example, the startTransition function marks the setItems update as non-urgent, allowing React to prioritize the text input update over the list update, ensuring a smoother user experience.
3. Suspense Improvements
React 18 brings significant improvements to Suspense, which was initially introduced in earlier versions to handle loading states for code-split components. In React 18, Suspense can now be used for data fetching, allowing components to wait for data to load before rendering.
Key Features:
Server-Side Rendering (SSR) Support: Suspense now works seamlessly with SSR, making it easier to build performant, data-driven applications.
Improved Loading States: By using Suspense, developers can create more granular loading states, improving the overall user experience.
Example:
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import React, { Suspense } from 'react'; const DataComponent = React.lazy(() => import('./DataComponent')); function App() { return ( <div> <Suspense fallback={<div>Loading...</div>}> <DataComponent /> </Suspense> </div> ); }
In this example, DataComponent is lazily loaded, and React will display the fallback content (Loading...) until the component is ready.
4. Automatic Batching of Updates
In React 18, Automatic Batching of state updates is enabled by default. This means that multiple state updates that occur within the same event handler or lifecycle method are batched together, leading to fewer renders and better performance.
Example:
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import { useState } from 'react'; function App() { const [count, setCount] = useState(0); const [text, setText] = useState(''); const handleClick = () => { setCount(count + 1); setText('Updated'); }; return ( <div> <button onClick={handleClick}>Click me</button> <p>{count}</p> <p>{text}</p> </div> ); }
In this example, both setCount and setText will be batched together, resulting in a single render instead of two separate renders, which improves performance.
5. Improved SSR with Streaming
React 18 introduces Streaming Server-Side Rendering (SSR), which allows HTML to be sent to the client in chunks as it's being generated. This improves the perceived load time for users, as they can start interacting with the page before the entire HTML is loaded.
Key Benefits:
Faster Time-to-Interactive: Streaming SSR reduces the time it takes for users to start interacting with the page.
Better Performance for Large Applications: Streaming SSR is particularly beneficial for large applications with heavy server-side logic.
Example:
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// Example server-side setup using Express import express from 'express'; import { renderToPipeableStream } from 'react-dom/server'; import App from './App'; const app = express(); app.get('/', (req, res) => { const { pipe } = renderToPipeableStream(<App />, { onShellReady() { res.statusCode = 200; res.setHeader('Content-type', 'text/html'); pipe(res); } }); }); app.listen(3000, () => { console.log('Server is running on http://localhost:3000'); });
In this example, the renderToPipeableStream function allows React to stream the HTML to the client, improving the page’s load time.
6. React 18 Compatible Libraries
React 18 introduces changes that might affect existing libraries. However, many popular libraries are being updated to support React 18’s new features, especially those related to concurrent rendering and Suspense.
Key Libraries:
React Query: Updated to work seamlessly with Suspense for data fetching.
Next.js: Provides built-in support for React 18's new features, including streaming SSR and Suspense.