Published: 5 September 2024
Introduction
React 18 introduced several groundbreaking features aimed at improving the performance and user experience of React applications. Suspense, Streaming, and Concurrent Rendering are three key features that significantly enhance React’s ability to manage complex, asynchronous tasks, while maintaining responsiveness and efficiency.
In this post, we’ll dive deep into these powerful features and explore practical use cases for each. Whether you’re building large-scale applications or looking to optimize your existing projects, understanding how to leverage these tools in React 18 will give you a competitive edge in 2024.
What’s New in React 18?
React 18 introduces several new features, but three stand out for their ability to handle rendering more efficiently: Suspense, Streaming, and Concurrent Rendering. These features focus on improving the overall performance of React apps, making them faster, more responsive, and capable of handling large datasets and complex user interactions seamlessly.
- Suspense: Suspense allows you to “pause” rendering until certain resources (like data or code) are ready. React 18 expands the use of Suspense, not only for code-splitting but also for data-fetching.
- Streaming: Streaming in React 18 allows you to stream parts of a page to the browser while others are still loading in the background. This reduces time-to-interactive and provides a faster initial rendering experience.
- Concurrent Rendering: This enables React to work on multiple tasks simultaneously. React can pause work on a low-priority task (like a background update) and focus on more urgent ones (like user input or critical UI updates).
1. Practical Use Case: Suspense for Data Fetching
Why Suspense?
Before React 18, data fetching typically involved using useEffect or libraries like React Query for asynchronous data loading. While this approach works, it doesn’t offer a great way to manage loading states across the app. Enter Suspense.
Suspense allows React to wait until all data is ready before rendering the component, reducing the need for multiple useState hooks to track loading states.
How to Use Suspense for Data Fetching
Let’s look at how you can use Suspense with data fetching in a Next.js app. You can use libraries like React Query or SWR in combination with Suspense for smoother and more efficient data handling.
Step 1: Setting Up Suspense with React Query
npm install react-query
Next, set up the React Query provider to enable Suspense-based data fetching:
// _app.tsx
import { QueryClient, QueryClientProvider } from 'react-query';
import { Suspense } from 'react';
const queryClient = new QueryClient();
function MyApp({ Component, pageProps }) {
return (
<QueryClientProvider client={queryClient}>
<Suspense fallback={<div>Loading...</div>}>
<Component {...pageProps} />
</Suspense>
</QueryClientProvider>
);
}
export default MyApp;
Step 2: Using Suspense for Fetching Data in a Component
In your page or component, you can now use Suspense to wrap asynchronous data fetching.
// products.tsx
import { useQuery } from 'react-query';
const fetchProducts = async () => {
const res = await fetch('/api/products');
return res.json();
};
const Products = () => {
const { data: products } = useQuery('products', fetchProducts);
return (
<div>
{products.map((product) => (
<div key={product.id}>
<h2>{product.name}</h2>
<p>{product.price}</p>
</div>
))}
</div>
);
};
export default Products;
Now, Suspense will ensure that the component waits for the data to load before rendering. No need for separate loading indicators or managing the loading state manually.
2. Practical Use Case: React 18’s Streaming for Faster Rendering
Why Streaming?
Streaming in React 18 enables you to start rendering a page as soon as the server sends over the first chunk of HTML, without waiting for the entire page to be ready. This is particularly useful for large applications with multiple routes or dynamic content.
With streaming, parts of the page are displayed even if the rest of the content is still being fetched or processed in the background. This results in faster time-to-first-byte (TTFB) and time-to-interactive (TTI), improving the user experience significantly.
How to Implement Streaming in Next.js
React 18’s new streaming capabilities can be used with Server-Side Rendering (SSR). Next.js already supports SSR out of the box, but with React 18’s streaming features, Next.js can now send partial HTML to the browser while it continues rendering the rest of the page.
Step 1: Enable React 18 Streaming in Next.js
First, ensure that your Next.js application is using React 18 and set it up for streaming. This involves enabling React’s Concurrent Mode in your next.config.js file.
// next.config.js
module.exports = {
experimental: {
reactRoot: true, // Enable React 18 concurrent rendering
},
};
Step 2: Streaming the Page
To enable streaming in your Next.js pages, you need to leverage React’s Suspense with a server-rendered component, similar to how we use Suspense for data fetching.
// pages/index.tsx
import { Suspense } from 'react';
const DynamicContent = React.lazy(() => import('../components/DynamicContent'));
const HomePage = () => (
<div>
<h1>Welcome to Our E-commerce Site!</h1>
<Suspense fallback={<div>Loading Featured Products...</div>}>
<DynamicContent />
</Suspense>
</div>
);
export default HomePage;
The DynamicContent component will load asynchronously, and React will stream its content without blocking the rendering of the rest of the page. By streaming the content, React can load the page faster and send a rendered, interactive page to the user quicker.
3. Practical Use Case: Concurrent Rendering for User Interactions
Why Concurrent Rendering?
React 18’s Concurrent Rendering allows React to work on multiple tasks simultaneously by prioritizing critical tasks (such as user input) while deferring less important ones (like background updates). This enables smoother user interactions without interruptions.
How to Use Concurrent Rendering in React 18
Concurrent rendering works behind the scenes, but you can manually trigger it using the startTransition API to mark non-urgent updates, such as search filtering or background data updates.
Step 1: Implementing startTransition for User Input
Let’s say you have a search bar that filters products in real time. You don’t want the filter operation to block other user interactions, such as clicking buttons or scrolling.
import { useState, startTransition } from 'react';
const Search = ({ products }) => {
const [query, setQuery] = useState('');
const [filteredProducts, setFilteredProducts] = useState(products);
const handleSearchChange = (e) => {
const value = e.target.value;
setQuery(value);
// Use startTransition to mark this update as low priority
startTransition(() => {
setFilteredProducts(
products.filter((product) => product.name.toLowerCase().includes(value.toLowerCase()))
);
});
};
return (
<div>
<input type="text" value={query} onChange={handleSearchChange} placeholder="Search products..." />
<ul>
{filteredProducts.map((product) => (
<li key={product.id}>{product.name}</li>
))}
</ul>
</div>
);
};
export default Search;
Here, startTransition allows React to prioritize the user’s typing interaction while updating the filtered results in the background. This ensures that the UI remains responsive, even during complex updates.
Conclusion
React 18’s Suspense, Streaming, and Concurrent Rendering features are game-changers for React developers, offering new ways to build faster, more responsive, and scalable applications. By using these tools effectively, you can significantly improve your app’s performance and user experience in 2024.
- Suspense simplifies data fetching and handling loading states, reducing the need for redundant loading components.
- Streaming allows you to send content to the browser incrementally, providing faster page loads and time-to-interactive.
- Concurrent Rendering ensures that your app remains responsive, even during large or complex updates.
As React continues to evolve, these features will play a crucial role in shaping the future of React applications, making it easier to build dynamic, performant, and highly interactive user interfaces.
