Published: 30 October 2023
Introduction
React has long been known for its powerful and efficient client-side rendering capabilities. However, in recent years, server-side rendering (SSR) has become an increasingly popular method for improving performance and SEO for React applications. The next big step in SSR is React Streaming — a feature that can greatly enhance the way data is fetched and rendered on the server.
With the introduction of Suspense for Data Fetching and Streaming SSR in React, developers now have powerful tools to optimize their apps, delivering content faster and making applications more responsive. This new approach allows content to be progressively streamed to the browser while the page is still being processed on the server, improving performance and user experience.
In this post, we’ll explore what React Streaming is, how it integrates with Suspense and SSR, and how you can implement Streaming SSR in Next.js to optimize your app’s performance.
What is React Streaming?
React Streaming is a new approach to server-side rendering that allows content to be progressively streamed to the browser, as it becomes available. In traditional SSR, the server waits until all content is ready before sending the entire HTML document to the client. With React Streaming, the server can send content as it’s generated, improving performance by delivering the initial HTML faster.
This progressive rendering is made possible by React Suspense and the new streaming APIs in React. Instead of blocking the entire page until all the data is loaded, React can now “suspend” certain parts of the UI, stream other parts of the page, and then continue to hydrate the remaining content.
Here’s what you gain with React Streaming:
- Faster Time to First Byte (TTFB): React can send content to the client progressively, reducing the initial load time.
- Improved User Experience: Users will see a fully rendered page sooner, even if some content is still loading in the background.
- Better Performance for Data-Heavy Apps: React Streaming is ideal for apps that need to fetch a lot of data (like dashboards or e-commerce sites) but want to minimize the delay in showing the initial page.
How React Streaming Improves Performance
React Streaming leverages Suspense and the React rendering engine to break up the rendering process into smaller, more manageable chunks. By allowing parts of the page to load in parallel, React can optimize which resources need to be loaded first and which can be deferred.
Key Benefits of React Streaming:
- Faster Loading: Instead of waiting for everything to load before rendering, React streams the content as it’s ready. This helps reduce the perceived load time for users.
- Non-blocking Rendering: Suspense allows React to pause rendering while it waits for async data to load, preventing unnecessary blocking of the UI and enabling quicker response times.
- Efficient Hydration: Hydration is the process of turning the static HTML from SSR into an interactive page. With React Streaming, hydration happens more efficiently because the content is already in place by the time the JavaScript bundle is loaded.
- Reduced Network Load: By streaming parts of the page to the client progressively, React can prioritize and fetch resources as needed, which reduces the amount of data the server needs to send initially.
How to Implement Streaming SSR in Next.js
Next.js, one of the most popular React frameworks for server-side rendering, fully supports React Streaming. Here’s a step-by-step guide on how to implement Streaming SSR in Next.js:
Step 1: Set Up Your Next.js Project
If you don’t already have a Next.js project, start by creating one.
npx create-next-app my-next-app
cd my-next-app
Step 2: Install the Necessary Dependencies
React Streaming is part of React 18, so ensure that your project is using React 18 or later.
Install the following:
npm install react@18 react-dom@18 next
Step 3: Enable Streaming SSR in Next.js
Streaming SSR in Next.js requires using React’s new Streaming APIs. Next.js already supports React Suspense and has experimental support for streaming out of the box. You’ll need to enable experimental features in your Next.js configuration.
In your next.config.js, enable the server components and suspense features:
// next.config.js
module.exports = {
experimental: {
reactRoot: true, // Enables React 18 features like Suspense and Streaming SSR
serverComponents: true, // Enables React Server Components (optional)
},
}
Step 4: Use Suspense for Data Fetching
React Suspense is essential for streaming SSR because it allows parts of the page to be “suspended” while data is fetched. You can use Suspense with data fetching libraries such as React Query, SWR, or custom hooks.
Here’s how you can use Suspense with React Query:
import React, { Suspense } from 'react';
import { useQuery } from 'react-query';
const fetchData = async () => {
const response = await fetch('/api/data');
return response.json();
};
const DataComponent = () => {
const { data } = useQuery('data', fetchData);
return <div>{data}</div>;
};
const Page = () => (
<Suspense fallback={<div>Loading...</div>}>
<DataComponent />
</Suspense>
);
export default Page;
Step 5: Stream Server-Side Content
When building a page in Next.js, you can use the getServerSideProps or getStaticProps function to fetch data on the server. However, React Streaming changes how this data is handled once it reaches the client.
Here’s how you might use Suspense and Streaming SSR together in a page component:
// pages/index.js
import React, { Suspense } from 'react';
import { useQuery } from 'react-query';
const fetchData = async () => {
const response = await fetch('/api/data');
return response.json();
};
const DataComponent = () => {
const { data } = useQuery('data', fetchData);
return <div>{data}</div>;
};
const Page = () => {
return (
<Suspense fallback={<div>Loading...</div>}>
<DataComponent />
</Suspense>
);
};
export async function getServerSideProps() {
// You can perform server-side fetching here for streaming SSR
return { props: {} };
}
export default Page;
Step 6: Optimize and Monitor Performance
Once you’ve set up Streaming SSR in your Next.js project, it’s time to optimize and monitor the performance of your app:
- Measure the Time to First Byte (TTFB): With Streaming SSR, you should see a significant improvement in the time it takes for the browser to receive the initial HTML from the server.
- Hydration Efficiency: With Streaming SSR, React can hydrate the app more efficiently, as only the critical parts of the app need to be rendered first.
- Monitor the Performance: Use tools like React DevTools and Web Vitals to measure and track the performance of your app. Look for improvements in metrics like First Contentful Paint (FCP) and Time to Interactive (TTI).
Conclusion
React Streaming is an exciting new feature that brings a huge performance boost to React apps, especially when combined with Suspense for data fetching. By implementing Streaming SSR in Next.js, you can provide faster load times, reduce network load, and improve the overall user experience.
In this post, we covered:
- How React Streaming improves performance by progressively rendering content.
- The role of Suspense in managing asynchronous data fetching in React.
- How to implement Streaming SSR in Next.js, enabling faster time to first byte and a smoother user experience.
As React continues to evolve, features like React Streaming and Server Components will become critical to building high-performance applications that delight users and deliver content faster than ever before.
