Mastering SSR and SSG in Next.js: A Comprehensive Guide

Introduction

Next.js, a powerful React framework developed by Vercel, offers multiple rendering strategies to optimize web applications for performance and SEO. Among these, Server-Side Rendering (SSR) and Static Site Generation (SSG) are pivotal. Understanding and implementing these can significantly enhance your application's efficiency and user experience.

🔹 What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) involves rendering your React components on the server for each request. This approach is ideal for pages that require dynamic data fetching and need to display up-to-date content on every visit. (Server-side Rendering (SSR) - Next.js)

Benefits of SSR:

• Dynamic Content: Fetches fresh data on each request, ensuring content is always up-to-date.

• SEO-Friendly: Pre-rendered HTML enhances search engine indexing.

• Improved Performance: Faster initial page load times for dynamic content. (Understanding Next.js: SSR, CSR, ISR and SSG - DEV Community)

Implementing SSR in Next.js:

To use SSR, export an async function named getServerSideProps from your page component. This function runs on the server for each request. (Server-side Rendering (SSR) - Next.js)

// pages/posts/[id].js
export async function getServerSideProps(context) {
  const { id } = context.params;
  const res = await fetch(`https://api.example.com/posts/${id}`);
  const post = await res.json();

  return {
    props: {
      post,
    },
  };
}

function Post({ post }) {
  return (
    <div>
      <h1>{post.title}</h1>
      <p>{post.content}</p>
    </div>
  );
}

export default Post;

In this example, getServerSideProps fetches post data based on the dynamic id parameter and passes it to the Post component as props.

🔹 What is Static Site Generation (SSG)?

Static Site Generation (SSG) pre-renders pages at build time, generating static HTML files. This method is suitable for pages with content that doesn't change frequently. (Rendering: Static Site Generation (SSG) - Next.js)

Benefits of SSG:

• High Performance: Pre-rendered pages load quickly.

• Scalability: Static files can be served via CDN, handling high traffic efficiently.

• SEO Optimization: Fully rendered HTML improves search engine visibility. (Rendering: Static Site Generation (SSG) - Next.js, Next.js: The Ultimate Guide to SSR and SSG in React - Medium)

Implementing SSG in Next.js:

Use getStaticProps to fetch data at build time. For dynamic routes, combine it with getStaticPaths. (Rendering: Static Site Generation (SSG) - Next.js)

// pages/posts/[id].js
export async function getStaticPaths() {
  const res = await fetch('https://api.example.com/posts');
  const posts = await res.json();

  const paths = posts.map((post) => ({
    params: { id: post.id.toString() },
  }));

  return { paths, fallback: false };
}

export async function getStaticProps({ params }) {
  const res = await fetch(`https://api.example.com/posts/${params.id}`);
  const post = await res.json();

  return {
    props: {
      post,
    },
  };
}

function Post({ post }) {
  return (
    <div>
      <h1>{post.title}</h1>
      <p>{post.content}</p>
    </div>
  );
}

export default Post;

Here, getStaticPaths defines the dynamic routes to pre-render, and getStaticProps fetches the necessary data for each page at build time.

🔹 Choosing Between SSR and SSG

Use Case Recommended Rendering Frequently updated content SSR Static content with rare updates SSG SEO-critical pages with dynamic data SSR Marketing pages, blogs, documentation SSG

Choose SSR when your page content changes frequently or depends on user-specific data. Opt for SSG when content is static and doesn't require real-time updates. (Static Site Generation (SSG) vs Server-Side Rendering in Next.js)

🔹 Combining SSR and SSG

Next.js allows combining SSR and SSG within the same application. For instance, you can statically generate most pages and use SSR for specific pages that require dynamic data.

Additionally, Next.js supports Incremental Static Regeneration (ISR), enabling you to update static content after deployment without rebuilding the entire site. (Understanding Next.js: SSR, CSR, ISR and SSG - DEV Community)

Conclusion

Mastering SSR and SSG in Next.js empowers you to build high-performance, SEO-friendly web applications tailored to your content's nature. By understanding when and how to implement each rendering strategy, you can optimize your application's performance and user experience. (SSR vs. SSG in Next.js: Differences, Advantages, and Use Cases)