Published at: February 10, 2021
In the world of web development, performance is key. As React continues to evolve, new features and tools are being introduced to make web apps faster and more efficient. One of the most exciting and innovative advancements is React Server Components. This feature promises to enhance server-side rendering (SSR) in React by allowing components to be rendered directly on the server, reducing the amount of client-side JavaScript required.
In this post, we’ll break down what React Server Components are, how they differ from traditional React components, and the performance benefits they bring to the table.
What Are React Server Components?
React Server Components are a new type of component that allows you to render part of your React app on the server instead of the client. This is different from traditional React components, which are rendered entirely in the browser.
In a typical React application, the entire React tree is rendered on the client side. React Server Components, on the other hand, allow for certain parts of the application to be rendered on the server, and only the necessary HTML and data are sent to the client. This leads to better performance, especially for large applications that can benefit from server-side rendering (SSR).
How Do Server Components Differ from Traditional React Components?
Here’s how Server Components stand apart from traditional React components:
- Rendering on the Server:
Unlike traditional React components, which are rendered on the client side, Server Components are rendered entirely on the server. The server sends HTML and data to the client, so there’s no need to download and execute the JavaScript for those components on the client side. - No Client-Side JavaScript:
Traditional React components require that JavaScript be downloaded and executed in the browser to render the component. Server Components, however, do not send JavaScript to the client. Only the HTML and necessary data are sent, which results in smaller JavaScript bundles and faster load times. - Mixed Rendering (Server + Client):
A React app can now have a mix of client-side components and server-side components. You can use Server Components where it makes sense (for example, in data-heavy or static parts of your app) while still having client-side React components that require interactivity. - No Rehydration:
Traditional SSR with React often requires “rehydration,” which means that React has to attach event handlers and state to pre-rendered HTML on the client side. Server Components do not require rehydration because they are rendered on the server and are sent as static HTML.
How Do React Server Components Work?
React Server Components integrate seamlessly into a React app. They can be used in combination with existing client-side React components, enabling developers to render certain parts of their app on the server for performance gains.
The Workflow:
- A Server Component is created in the same way as a normal React component but is marked as a “server component” using a special API.
- The server renders the component to HTML, then sends the HTML and data to the client.
- The client receives the HTML and data, which allows for fast loading without the need for downloading large JavaScript bundles.
- Since no JavaScript is sent to the client for these components, they do not have client-side interactivity or state. This is ideal for parts of the app that don’t need to be interactive, such as static content or data-heavy components like tables or lists.
Performance Benefits of React Server Components
The most obvious benefit of React Server Components is the improvement in performance. Here are some ways Server Components help boost the performance of your React app:
- Smaller JavaScript Bundles:
Since Server Components don’t send JavaScript to the client, your app’s JavaScript bundle size is significantly reduced. This leads to faster load times, especially on slower network connections. - Faster Initial Load:
Server Components allow the initial HTML to be rendered and sent to the client quickly, without waiting for client-side JavaScript execution. This reduces the time to first paint (TTFP) and improves the perceived performance of the app. - Reduced Client-Side Rendering:
With traditional SSR, you need to rehydrate the app in the client after sending the HTML. With Server Components, there’s no need for rehydration, reducing the amount of JavaScript processing on the client side. - Better Resource Utilization:
By moving some rendering logic to the server, React Server Components allow the client to focus on interactivity and dynamic updates, rather than being bogged down by rendering and data-fetching tasks.
Real-World Applications of React Server Components
So, where can you use React Server Components? Here are a few real-world examples of how they can be beneficial:
- Data-Heavy Pages:
For apps that display large data sets, such as product listings, dashboards, or tables, Server Components can help by rendering the data on the server and sending it to the client as pre-rendered HTML. This reduces the amount of client-side JavaScript needed to render these pages. - Static Content:
For parts of your app that don’t change often (like marketing pages, articles, or static content), Server Components can render the content on the server and send it to the client without requiring client-side rendering. - SEO and Performance Optimization:
Server Components are ideal for SEO-sensitive pages that need to be pre-rendered for search engine bots. They also benefit performance since there’s less client-side rendering involved. - Simplifying Code-Splitting:
By moving parts of the app that don’t require interactivity to the server, you can reduce the need for complex client-side code-splitting techniques. This keeps your app more manageable and simplifies bundling.
Conclusion
React Server Components are a game-changing feature that brings server-side rendering to React in a new, more efficient way. By allowing certain components to be rendered on the server without sending JavaScript to the client, Server Components reduce the amount of code needed on the client side, resulting in faster load times, improved performance, and smaller JavaScript bundles.
As React continues to innovate, Server Components provide a new way to optimize your React apps for performance without compromising on the dynamic, interactive experience that React is known for.
If you’re looking to improve your app’s performance, server-side rendering with React Server Components is definitely worth exploring.
