Server-Side Rendering vs Client-Side Rendering

What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) is a method of rendering a web page’s content on the server before sending it to the client. When a user requests a page, the server generates the HTML, CSS, and JavaScript, then sends the fully rendered content to the browser. This means the user sees a fully formed page almost instantly, without waiting for JavaScript to load and execute.

How SSR Works

The user makes a request to the server.
The server processes the request and renders the HTML, CSS, and JavaScript for the page.
The server sends the rendered content to the client’s browser.
Once the content is loaded, the client-side JavaScript takes over (hydration) to allow interaction.

Benefits of SSR

Faster Initial Load: Since the HTML is pre-rendered on the server, the page content is visible to users immediately. This can lead to faster page load times for users, especially on slower networks.
Better SEO: Search engines can easily crawl and index the fully rendered HTML, which improves SEO.
Improved User Experience: Users see content faster, as the browser doesn’t have to wait for JavaScript to download and execute before rendering the page.

Example of SSR in React (using Next.js)

// pages/index.js in a Next.js app
import React from "react";
 
const Home = ({ message }) => {
  return <h1>{message}</h1>;
};
 
export async function getServerSideProps() {
  // Fetch data on the server
  const message = "Hello from the server-side!";
  return { props: { message } };
}
 
export default Home;

In this example, Next.js pre-renders the page on the server and sends the fully rendered content to the browser. The getServerSideProps function is called on the server before rendering the page.

What is Client-Side Rendering (CSR)?

Client-Side Rendering (CSR) is a method where the browser downloads the JavaScript bundle and renders the page entirely on the client side. When a user requests a page, the server sends only the basic HTML and the JavaScript files. The browser then downloads and executes the JavaScript to render the content on the page.

How CSR Works

The user makes a request to the server.
The server responds with an empty HTML page and JavaScript files.
The browser downloads and executes the JavaScript to generate the content.
The user sees the fully rendered page after the JavaScript has executed.

Benefits of CSR

Interactive and Dynamic: CSR is ideal for building single-page applications (SPAs) with rich interactions, as the JavaScript can dynamically update the UI without reloading the page.
Faster Subsequent Navigations: After the initial page load, navigation between different pages is usually faster because only data needs to be fetched, not the entire HTML.
Reduced Server Load: Since the rendering is done on the client side, there is less load on the server.

Example of CSR in React

import React, { useState, useEffect } from "react";
 
const App = () => {
  const [message, setMessage] = useState("");
 
  useEffect(() => {
    // Simulate fetching data on the client-side
    setMessage("Hello from the client-side!");
  }, []);
 
  return <h1>{message}</h1>;
};
 
export default App;

In this example, the page’s content is rendered entirely on the client side using React’s useEffect hook to simulate fetching data.

When to Use SSR

SEO-Heavy Websites: If SEO is a priority for your site (e.g., blogs, e-commerce), SSR is the better choice because it ensures search engines can easily crawl and index your content.
Faster Initial Load: SSR can improve the perceived performance of your website by reducing the time it takes for the user to see the content, especially for first-time visitors.
Content-Rich Sites: For sites with a lot of static content, such as news websites or documentation pages, SSR ensures that users can see the content without waiting for JavaScript to render it.

When to Use CSR

Single-Page Applications (SPAs): CSR is perfect for SPAs where the UI needs to be highly interactive, and the application state changes frequently based on user interactions.
Dynamic User Interfaces: If your site requires a lot of dynamic updates or interactions, such as dashboards or real-time updates, CSR allows for smooth client-side rendering without the need for server round-trips.
Reduced Server Load: CSR can be more efficient when you want to offload the work from the server to the client, especially for highly dynamic applications.

Can You Use Both?

Yes! Many modern frameworks like Next.js and Gatsby support both SSR and CSR. This allows you to combine the benefits of both approaches, depending on the specific requirements of your application. You can render the initial page on the server for better SEO and performance, and then switch to CSR for subsequent page navigation and dynamic updates.

Conclusion

Both Server-Side Rendering (SSR) and Client-Side Rendering (CSR) have their advantages and are suited to different use cases. SSR is great for SEO, faster initial page loads, and static content, while CSR is better for dynamic, highly interactive applications that don’t need to be indexed by search engines. Understanding when and how to use each will help you build faster, more efficient, and more scalable web applications.

Still undecided on which rendering approach to choose? Think about your app’s needs: Is SEO and fast initial load a priority, or do you need a highly interactive experience? Make the decision based on your project’s goals!

Server-Side Rendering vs Client-Side Rendering - Which One Should You Use?