Incremental Static Regeneration (ISR) in Next.js: Building Scalable Websites

Incremental Static Regeneration (ISR) is a powerful feature in Next.js that allows you to update static pages after they’ve been built, without rebuilding the entire site. This is particularly useful for large sites with thousands of pages, where rebuilding the entire site would be time-consuming and inefficient. In this article, we’ll explore how ISR works in Next.js, how to implement it, and why it’s a game-changer for building scalable websites.

What is Incremental Static Regeneration?

Incremental Static Regeneration (ISR) is a technique that allows you to update static pages after they’ve been built, without requiring a full rebuild of the site. This is achieved by revalidating pages in the background and regenerating them as needed. ISR is ideal for content that changes frequently but doesn’t need to be updated in real-time, such as blog posts, product listings, or news articles.

How Incremental Static Regeneration Works in Next.js

In Next.js, ISR is implemented using the revalidate option in the getStaticProps function. This option specifies the number of seconds after which a page should be revalidated and regenerated.

Using the revalidate Option

To enable ISR, add the revalidate option to the getStaticProps function. Here’s an example:

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

  return {
    props: {
      post,
    },
    revalidate: 10, // Revalidate the page every 10 seconds
  };
}

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

In this example, the revalidate option is set to 10 seconds, meaning the page will be revalidated and regenerated every 10 seconds if necessary.

Benefits of Incremental Static Regeneration

Incremental Static Regeneration offers several benefits:

• Scalability: ISR allows you to build large sites with thousands of pages without requiring a full rebuild.
• Performance: Static pages are served as HTML files, resulting in faster load times and better performance.
• Fresh Content: ISR ensures that your content is always up-to-date without sacrificing performance.

Secrets and Hidden Facts

• Fallback Pages: Use the fallback option in getStaticPaths to generate pages on-demand.
• Custom Error Pages: Create a 404.js file in the pages directory to customize the 404 error page for ISR.
• Combining ISR with SSR: Next.js allows you to combine ISR with Server-side Rendering (SSR) for hybrid applications.

Conclusion

Incremental Static Regeneration is a powerful feature in Next.js that allows you to update static pages after they’ve been built, without requiring a full rebuild of the site. Whether you’re building a blog, an e-commerce platform, or a news site, ISR provides the tools and flexibility you need to create scalable and performant websites.