This content originally appeared on Level Up Coding – Medium and was authored by Harsha attray
Introduction
React has for a long period been a key component in the building of dynamic, interactive web apps. With each newer release, a variety of novel features makes modern web development an ever-changing world. Perhaps one of the most exciting things coming to React 19 will be React Server Components, a new hybrid way to do server and client rendering. This might just become game-changing in how developers are going to build up their apps.
This article will go into deeper detail about React Server Components: what they are, how it works, the benefits and limitations, best practices when using them, with code examples. That will give us better insights into how to leverage RSCs in our work.
What Are React Server Components?
React Server Components are a new way to construct components with React, but this time they are rendered on the server and sent to the client as serialized HTML. While CSR does all the heavy lifting of rendering an entire component tree directly within the browser, and SSR populates the first wave of HTML on the server, RSCs have a unique capability to have certain parts of the UI rendered only in the server and then sent down as pure HTML to a client. This approach keeps the client-side JavaScript at a minimum and improves performance; hence, applications powered with React are leaner and faster.
Core Characteristics of React Server Components
No Client-Side JavaScript: In the case of RSCs, the output of the render function gets serialized as HTML and then sent to the client. In other words, there is no client-side JavaScript logic for these components, hence decreasing the bundle size in general.
Server-Side Capabilities: Server Components can directly interact with server-side resources, including databases, file systems, and backend APIs. It implies that you run your server-only logic, such as database queries, directly within these components.
Seamless integration with Client Components: RSCs will coexist and interoperate with the traditional Client Components. You, as a developer, would then be able to decide which of the components should be rendered at the server and which ones should handle client-side interactions.
Reduced Overhead of Data Fetching: Since server components can directly access the data on the server, there will be no need to use useEffect or any other client-side hook for fetching data. This will result in cleaner and more efficient code.
Streaming Capabilities: Server Components are also capable of streaming incrementally to the client, meaning parts of the UI can be rendered and displayed at the same time as other parts are being fetched or processed on the server.
How React Server Components Work
The react-runtime, when using RSCs sends the Server-side rendered HTML and a payload of the data across to the client. This payload is then used to hydrate the client which may also be further integrated with Client Components if necessary.
Here’s a basic diagram to outline the flow:
The browser makes a request to the server to load a React Server Component.
The server fetches whatever data is required and renders the component as HTML and sends back the result to the browser.
The client receives the HTML and renders in the browser without requiring more JavaScript.
This above flow doesn’t require shipping extra JavaScript logic to the client; hence, this would be perfect for those scenarios where initial page load performance is crucial and SEO.
Advantages of React Server Components
1. Smaller Client-Side Bundle Size
React Server Components allows you to render the static, non-interactive part of your application on the server, so no need to send JavaScript logic to the client. That results in smaller client bundles, smaller downloads, and faster runtime performance on the client. Example: Bundle Size Reduction Using RSCs
Lets imagine a component that fetches a list of products and renders them as static HTML. With RSCs you can do the fetching on the server and only send the rendered HTML to the client
// src/components/ProductList.server.jsx
import React from 'react';
import db from '../utils/db';
export default async function ProductList() {
const products = await db.getProducts();
return (
<ul>
{products.map(product => (
<li key={product.id}>
<h2>{product.name}</h2>
<p>{product.description}</p>
</li>
))}
</ul>
);
}
In this example, the ProductList component fetches product data from a server-side database and renders it as HTML. The client only receives the HTML and doesn’t need to include any JavaScript for fetching or managing state.
2. Improved SEO and Initial Page Load
By sending fully rendered HTML, server-rendered components help with SEO by immediately making content visible to search crawlers. This also reduces TTFB (Time to First Byte) and improves initial page load time.
Example: Static Content with RSCs for SEO
Suppose you have a blog post component that you want instantly visible on page load:
// src/components/BlogPost.server.jsx
import React from 'react';
import fs from 'fs';
export default async function BlogPost({ postId }) {
const markdownContent = await fs.promises.readFile(`./content/${postId}.md`, 'utf8');
return <div dangerouslySetInnerHTML={{ __html: markdownContent }} />;
}
Above component reads a markdown file from server’s file system, converts it into HTML and sends the result to the client. Client receives fully rendered HTML which is great for SEO and perceived load time.
3. Simpler Data Management
By moving data-fetching logic into the server, RSCs drastically reduce the need for complicated client-side state management or effect hooks like useEffect. This keeps things tidy and diminishes the need for numerous network requests
Example: Fetching Data with Server Components
// src/components/UsersList.server.jsx
import React from 'react';
import fetch from 'node-fetch';
export default async function UsersList() {
const response = await fetch('https://jsonplaceholder.typicode.com/users');
const users = await response.json();
return (
<ul>
{users.map(user => (
<li key={user.id}>
{user.name} - {user.email}
</li>
))}
</ul>
);
}
This component fetches the data directly from an external API and then renders a list of users right on the server. On the client side, no Data-fetching hooks or state management are required.
4. Better Server Resource Utilization
Because RSCs execute on the server, they have access to certain server-side resources like database connections, file system access, and environment variables without the need for direct exposure to the client. All this, in turn, further reduces the need to make round trips from client to server and minimizes resources used on the client.
Limitations and Trade-Offs
While React Server Components come with several advantages, they come with some of the limitations listed below
1. Lack of Interactivity
Server Components need to be static themselves and are unable to manage any client-side state or handle events upon user interactions such as clicks or form submits. You’d have to combine them with Client Components for such purposes.
Example: Combining Server and Client Components
// src/components/ProductItem.client.jsx
import React, { useState } from 'react';
export default function ProductItem({ product }) {
const [quantity, setQuantity] = useState(1);
return (
<div>
<h2>{product.name}</h2>
<p>{product.description}</p>
<input
type="number"
value={quantity}
onChange={e => setQuantity(e.target.value)}
/>
<button onClick={() => alert(`Adding ${quantity} items to cart`)}>Add to Cart</button>
</div>
);
}
It can be reused next to a server-side rendered ProductList component, adding interaction to it without including the fetch-products logic on the client.
2. Higher Server Load
By transferring more and more rendering logic onto the server, that automatically means higher server load. This will likely be more expensive or require more performing infrastructure. Remember balancing server-side and client-side rendering depending on your app needs and expected traffic.
3. Compatibility with Third-Party Libraries
Most of the React libraries don’t work with RSCs, especially when third-party libraries rely on client-side features like useEffect or other third-party Hooks. And that again leaves you with very limited choices while integrating existing libraries, and may require refactoring or avoidance of those libraries altogether.
4. Limited Debugging Tools
Well, debugging is a bit trickier because RSCs are rendered on the server. While tools like the React DevTools can support a little in respect to client-side debugging, at times server-rendered components may need additional server-side debugging tools and techniques.
When to Use React Server Components
RSCs are particularly useful under certain scenarios:
- Static Content Rendering: Pages or sections of your application that contain mainly static content-such as documentation pages or landing pages.
- SEO-Focused Applications: Content-heavy sites where SEO is critical, as RSCs ensure the search engines will see all the content.
- Content Delivery with Low Interactivity: RSCs should be used on pages where the delivery of content is not highly interactive on the client side, for example, some product detail pages or blog posts.
When Not to Use React Server Components
One should refrain from using RSC in scenarios such as:
Highly Interactive Applications: Applications such as chat apps, collaboration tools, or any other highly interactive UI that would involve very complex client-side state management.
- Offline-First or Low Connectivity Scenarios: Applications that need to work offline or on low server connectivity .
- Real-Time Applications: Components that update frequently or real-time synchronizations are needed, such as live feeds or dashboards.
Conclusion
React Server Components are a powerful addition to the React ecosystem in React 19. They allow developers to build faster, more efficient, and SEO-friendly applications by moving rendering logic to the server. However, as with any new technology, it’s important to understand its limitations and use it where it fits best.
A Glimpse into React Server Components was originally published in Level Up Coding on Medium, where people are continuing the conversation by highlighting and responding to this story.
This content originally appeared on Level Up Coding – Medium and was authored by Harsha attray