Static Site Generation (SSG) for Performance

Static Site Generation (SSG) is one of the most popular methods for pre-rendering a web application. It generates HTML files at build time, making it faster and more performant by serving pre-rendered pages to the user. Next.js makes it incredibly easy to implement SSG, offering built-in features like getStaticProps and getStaticPaths to generate static pages for your app. This approach ensures that your content is served as static HTML, resulting in faster page loads, improved SEO, and a better user experience.

Let’s dive into the concept of Static Site Generation (SSG) and how it can be used in Next.js to improve performance.

1. What is Static Site Generation (SSG)?

SSG is the process of generating static HTML pages at build time, rather than on each request. When you deploy an SSG-based application, the content is rendered once during the build process and saved as static files, which are then served to the user whenever they visit the site.

This approach differs from Server-Side Rendering (SSR), where the HTML is generated on each request, and Client-Side Rendering (CSR), where JavaScript is used to render the content after the page has loaded.

2. Why Use SSG?

Performance: Static pages are served directly by a CDN (Content Delivery Network), ensuring fast page load times.
SEO: Since the content is already rendered when it reaches the browser, it’s more crawlable by search engines, improving SEO.
Reliability: Static sites are not dependent on server-side processes for each request, making them less prone to server issues or downtime.
Cost Efficiency: Static sites can be served cheaply through CDNs, reducing infrastructure costs.

3. How to Implement SSG in Next.js

Next.js makes it incredibly easy to generate static pages with getStaticProps for fetching data at build time and getStaticPaths for dynamic routes.

a) Static Pages with `getStaticProps`

Create a new page (e.g., pages/index.js).
Fetch data at build time using getStaticProps: // pages/index.js export async function getStaticProps() { // Fetch data from an API, database, or local file const res = await fetch('https://jsonplaceholder.typicode.com/posts'); const posts = await res.json(); return { props: { posts }, }; } const HomePage = ({ posts }) => { return ( <div> <h1>Static Site Generation with Next.js</h1> <ul> {posts.map((post) => ( <li key={post.id}>{post.title}</li> ))} </ul> </div> ); }; export default HomePage;

In this example:

getStaticProps fetches the list of blog posts at build time and passes them as props to the page component.
The posts are rendered as static HTML when the page is built.

Run the Build Command: To see the effect of SSG, you’ll need to build the Next.js app: npm run build npm run start After running the build, the page content will be pre-rendered into static HTML and served as fast as possible.

b) Dynamic Routes with `getStaticPaths` and `getStaticProps`

For dynamic routes (e.g., blog posts), you can combine getStaticPaths and getStaticProps to generate static pages for each route.

Create a dynamic route (e.g., pages/posts/[id].js):
Add getStaticPaths to define which pages to generate at build time: // pages/posts/[id].js export async function getStaticPaths() { // Fetch a list of blog post IDs const res = await fetch('https://jsonplaceholder.typicode.com/posts'); const posts = await res.json(); // Get paths for each post based on the IDs const paths = posts.map((post) => ({ params: { id: post.id.toString() }, })); return { paths, fallback: false, // Use false for not found paths }; } export async function getStaticProps({ params }) { const { id } = params; const res = await fetch(`https://jsonplaceholder.typicode.com/posts/${id}`); const post = await res.json(); return { props: { post }, }; } const PostPage = ({ post }) => { return ( <div> <h1>{post.title}</h1> <p>{post.body}</p> </div> ); }; export default PostPage;

Here:

getStaticPaths fetches the list of posts and generates paths for each one based on their id.
getStaticProps fetches the data for each individual post at build time and passes it to the page component.

Build and Test the Dynamic Pages: After running npm run build, static pages will be generated for each blog post based on the id. These pages are served directly from the CDN or server as static HTML files.

4. Performance Benefits of SSG

By utilizing SSG, Next.js provides a highly performant application that can be easily scaled. Let’s break down how SSG helps with performance:

Instant Load Time: Since the HTML is pre-rendered, the browser doesn’t need to wait for JavaScript to execute and render the content. This results in faster initial load times.
Reduced Server Load: With static pages, there is no need to run server-side logic or make database queries on every request.
CDN Caching: Static content can be cached at the edge by CDNs, ensuring that users from different regions can access the site with minimal latency.

5. When to Use SSG in Next.js

SSG is ideal in the following scenarios:

Content that doesn’t change frequently: If your pages have content that rarely updates (e.g., blog posts, marketing pages, documentation), SSG is a great fit.
SEO Optimization: SSG ensures that content is fully rendered when it reaches the browser, which is crucial for SEO and ensuring that search engines can crawl your pages.
Faster Performance: By serving static files from a CDN, SSG dramatically improves performance, which is especially beneficial for large-scale websites or applications.

6. Considerations for SSG in Next.js

Build Time: If you have a large number of pages to generate, the build process can take a long time. Consider optimizing data fetching or using incremental static regeneration (ISR) if the content changes infrequently but still needs to be updated periodically.
Data Freshness: SSG is best for content that doesn’t change often. For dynamic data that updates frequently (e.g., user dashboards or real-time content), SSR or client-side rendering might be more appropriate.
Incremental Static Regeneration (ISR): Next.js supports ISR, which allows you to update static pages without rebuilding the entire site. You can define a revalidation interval to regenerate specific pages at a certain frequency.

7. Incremental Static Regeneration (ISR)

With ISR, Next.js allows you to update static content after build time without rebuilding the entire site. This is useful for large sites where content might change, but you don’t need to rebuild every page.

Here’s how you can use ISR in Next.js:

export async function getStaticProps() {
  const res = await fetch('https://jsonplaceholder.typicode.com/posts');
  const posts = await res.json();

  return {
    props: { posts },
    revalidate: 10, // Rebuild the page every 10 seconds
  };
}

In this case, the page will be regenerated every 10 seconds, ensuring that the content is up to date without requiring a full rebuild.