In the current era of web development, the way that a webpage is rendered has a significant impact on performance, SEO, and user experience. These days, two main rendering methods are brought to use: server-side rendering (SSR) and client-side rendering (CSR). Each method has its pros and cons, and taking the time to select the right rendering method may drastically affect the performance and overall experience of a web application.

Server-side rendering (SSR) refers to generating the HTML on the server and sending a fully rendered page to the browser. This process ensures faster initial page loads and improved SEO, making it an excellent choice for content-heavy websites and applications that rely on search engine indexing. However, SSR may come with increased server costs and a slightly longer TTFB (Time to First Byte) due to backend processing.

Client-side rendering (CSR) begins with a lightweight HTML page and leverages JavaScript to retrieve and build the content experience dynamically in the client. This approach is often used in single-page applications (SPAs) when interactivity is a priority and full-page UIs are not desired. Although CSR lightens the load on the server and enhances the interactive experience with the user, CSR may negatively impact initial load times and search engine optimization (SEO) if not optimized effectively.

It is valuable for developers to understand how these rendering techniques differ in order to make an educated decision. In this guide, we will compare SSR and CSR in detail, including the advantages, disadvantages, when to use them, and code examples. By the end of this blog, you will be able to determine which rendering method can be used for your project.

What is Server-Side Rendering (SSR)?

Server-side rendering (SSR) is a technique where the HTML content is generated on the server before being sent to the client. This means the browser receives a fully rendered page, reducing the time needed to display meaningful content to the user.

How SSR Works

1. The browser requests a webpage from the server.

2. The server processes the request, generates the HTML, and fetches required data.

3. The fully rendered HTML is sent to the client.

4. The browser displays the content almost instantly.

5. JavaScript takes over to handle interactivity.

Example of SSR in Next.js:

import React from 'react';
export async function getServerSideProps() {
  const res = await fetch('https://jsonplaceholder.typicode.com/posts/1');
  const post = await res.json();
  return {
    props: { post },
  };
}
export default function Post({ post }) {
  return (
    <div>
      <h1>{post.title}</h1>
      <p>{post.body}</p>
    </div>
  );
}

In the above example, getServerSideProps fetches data on the server for every request, ensuring that the latest data is displayed.

Advantages of SSR:

• Faster initial load time as HTML is pre-generated.

• Better SEO since search engine crawlers can easily parse the content.

• Ideal for dynamic content that requires real-time updates.

Disadvantages of SSR:

• Increased server load as every request triggers rendering.

• Slower TTFB compared to static site generation.

• More complex backend setup is required.

What is client-side rendering (CSR)?

Client-Side Rendering (CSR) shifts the rendering process to the browser. Instead of receiving a fully rendered page from the server, the client receives a basic HTML file along with JavaScript, which dynamically populates the page content.

How CSR Works

1. The browser requests a webpage from the server.

2. The server sends a minimal HTML file along with JavaScript.

3. JavaScript fetches data and renders content dynamically.

4. The page becomes interactive after JavaScript execution.

Example of CSR with React:

import React, { useEffect, useState } from 'react';
export default function Post() {
  const [post, setPost] = useState(null);
  useEffect(() => {
    fetch('https://jsonplaceholder.typicode.com/posts/1')
      .then(response => response.json())
      .then(data => setPost(data));
  }, []);
  if (!post) return <p>Loading...</p>;
  return (
    <div>
      <h1>{post.title}</h1>
      <p>{post.body}</p>
    </div>
  );
}

In this example, data is fetched after the component mounts, which may result in a short delay before content appears.

Advantages of CSR:

• Reduced server workload, making it cost-efficient.

• Enhanced interactivity and seamless user experience.

• Ideal for SPAs where only parts of the UI need updating.

Disadvantages of CSR:

• Slower initial page load due to JavaScript execution.

• Poor SEO performance unless handled with SSR techniques like hydration.

• More dependency on JavaScript, which may cause issues for users with disabled scripts.

When to Use SSR vs. CSR?

Hybrid Approaches: Best of Both Worlds

Some modern frameworks allow a hybrid approach where SSR and CSR can be combined. For example, Next.js supports static site generation (SSG) and incremental static regeneration (ISR), which provide a balance between performance and interactivity.

Example: Combining SSR & CSR in Next.js

import { useEffect, useState } from 'react';
export async function getServerSideProps() {
  return {
    props: { initialData: 'Server Rendered Content' },
  };
}
export default function Hybrid({ initialData }) {
  const [clientData, setClientData] = useState(null);
  useEffect(() => {
    setClientData('Client Rendered Content');
  }, []);
  return (
    <div>
      <p>{initialData}</p>
      <p>{clientData || 'Loading...'}</p>
    </div>
  );
}

This hybrid approach ensures fast initial loads while dynamically updating parts of the page on the client side.

Conclusion

Choosing between server-side rendering (SSR) and client-side rendering (CSR) depends on the nature of your application, performance needs, and SEO requirements. SSR provides better initial load times and SEO advantages, making it ideal for content-heavy websites. However, it demands more server resources.

CSR, on the other hand, enhances interactivity and scalability, making it a great fit for SPAs and applications that require high user engagement. The trade-off is slower initial page loads and SEO concerns.

In general, many modern applications take a hybrid approach to deal with the strengths and weaknesses of both SSR and CSR, and hybrid applications aim to build performant, scalable web applications that are also friendly to SEO. If you plan to use these methods, it is important to understand when you should use each type to provide your users with the most efficient and effective web experience.

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