Building High-Performance React Applications with React Server Components

React Server Components is a new feature introduced in React 18 that allows developers to render React components on the server, and then stream them to the client. This can improve performance and reduce the amount of JavaScript that needs to be downloaded and executed on the client. In this article, we’ll take a closer look at React Server Components and provide some code examples to demonstrate how they work.

What are React Server Components?

React Server Components allow developers to render React components on the server, and then stream them to the client. This is similar to server-side rendering, but with React Server Components, the server can generate dynamic content that is specific to each individual user.

The server generates a stream of HTML that includes the React components, along with the data they need to render. The client then receives this stream and starts rendering the components immediately, even before all the data has been downloaded.

This can significantly reduce the time it takes for the user to see something on the screen, and it can also reduce the amount of JavaScript that needs to be downloaded and executed on the client.

How do React Server Components work?

To use React Server Components, you’ll need to make some changes to your code. First, you’ll need to create a server entry point that exports a function that takes a request and returns a promise that resolves to the stream of HTML.

Here’s an example:

import { createServerRenderer } from 'react-server-dom-webpack';

import App from './App';
export default createServerRenderer(request => {
  return {
    html: <App />,
    // Any data that the server wants to pass to the client can be included here
    // This data can be used to hydrate the components on the client
    // See the "hydrate" example below for more details
    data: {},
  };
});

In this example, we’re using the createServerRenderer function from the react-server-dom-webpack package to create a server renderer.

We’re also exporting a function that takes a request and returns an object that contains the HTML to be streamed to the client, along with any data that the server wants to pass to the client.

Next, we’ll need to make some changes to our client code. Specifically, we’ll need to use the useDeferredValue hook to asynchronously render the React components on the client.

Here’s an example:

import { useDeferredValue, hydrate } from 'react-server-dom-webpack';

import App from './App';
// This is the data that was passed from the server
const data = window.__REACT_SERVER_COMPONENTS_DATA__;
// We'll use the "hydrate" function to asynchronously render the components on the client
hydrate(() => {
  // We'll use the "useDeferredValue" hook to defer rendering until the data is available
  const deferredData = useDeferredValue(data);
  return <App data={deferredData} />;
});

In this example, we’re using the hydrate function from the react-server-dom-webpack package to asynchronously render the React components on the client.

We’re also using the useDeferredValue hook to defer rendering until the data is available. This ensures that the client only starts rendering the components once all the data has been downloaded.

Finally, we’re passing the deferred data to our App component, which can use it to render the components.

Conclusion

React Server Components are a powerful new feature that can significantly improve the performance and usability of React applications. By rendering components on the server and streaming them to the client, React Server Components can reduce the time it takes for the user to see something on the screen, and it can also reduce the amount of JavaScript that needs to be downloaded and executed on the client. With the code