Imagine you’re building an e-commerce platform with thousands of products. You want the lightning-fast load times of Static Site Generation (SSG) for better SEO and user experience, but your product details and inventory frequently change. How do you strike the right balance between speed and keeping the content fresh? Enter Incremental Static Regeneration (ISR), and with Next.js 15, it just got better.
In this blog, we’ll explore the concept of ISR, walk through how it works, and dive into the impactful updates in Next.js 15 that change the way developers approach code. To make things practical, we’ll follow a single example of building a product listing page.
What is ISR?
ISR allows you to update static pages incrementally, without rebuilding the entire site. This means you can have the performance benefits of static pages while keeping content fresh. The pages are regenerated in the background at a defined interval or when specific triggers are met.
Key Benefits:
- Scalability: No need to rebuild your entire site for small updates.
- Performance: Users still get the speed of static pages.
- Flexibility: Updates happen automatically in the background.
Workflow of Incremental Static Regeneration (ISR) in Next.js
The diagram above illustrates the workflow of ISR in Next.js. It shows how static pages are served, regenerated in the background, and revalidated to ensure fresh content.
Let’s Build: Product Listing with ISR
To understand ISR, we’ll build a product listing page for an e-commerce site. Here’s how it evolves step by step:
Step 1: Setting Up Static Generation
Initially, we create a product listing page using Static Site Generation (SSG). The page fetches data during build time and remains static.
// pages/products.js
import { getProducts } from '../lib/api';
export async function getStaticProps() {
const products = await getProducts();
return {
props: {
products,
},
};
}
export default function Products({ products }) {
return (
<div>
<h1>Product Listings</h1>
<ul>
{products.map((product) => (
<li key={product.id}>{product.name}</li>
))}
</ul>
</div>
);
}
This works perfectly for a fixed set of products, but what if we add new products or update existing ones frequently? Users would see outdated data until we rebuild the site. This is where ISR steps in.
Step 2: Introducing ISR
With ISR, we can specify how often the static pages should regenerate in the background. Let’s add a revalidation period to our product listing page.
export async function getStaticProps() {
const products = await getProducts();
return {
props: {
products,
},
revalidate: 60, // Regenerate the page every 60 seconds
};
}
Now, the page regenerates every 60 seconds. If you add or update a product in your database, users will see the changes after the revalidation period, without requiring a full site rebuild.
What’s New in Next.js 15 for ISR?
Next.js 15 introduces several updates that make ISR even more powerful and efficient:
1. Dynamic Revalidation with API Control
In previous versions, ISR revalidation was strictly time-based. With Next.js 15, you can programmatically trigger revalidation through APIs. This means developers can regenerate pages whenever specific events occur, such as updating a product in the database.
Example: Revalidate on Demand
export default async function handler(req, res) {
if (req.method === 'POST') {
await res.revalidate('/products'); // Revalidate the product listing page
res.status(200).json({ message: 'Revalidated!' });
} else {
res.status(405).json({ message: 'Method not allowed' });
}
}
2. Optimized Cache Invalidation
Next.js 15 optimizes cache invalidation, ensuring that stale pages are replaced efficiently without affecting other static pages. Developers now have better control over which pages need to be regenerated.
Step 3: Updating our Example with Dynamic Revalidation
Let’s say you have an admin dashboard where products can be added or edited. You can hook into the Next.js revalidation API to trigger updates immediately after a change.
// Trigger revalidation from your admin dashboard
const handleUpdate = async () => {
await fetch('/api/revalidate', {
method: 'POST',
});
alert('Page revalidated successfully!');
};
// Button in your admin panel
<button onClick={handleUpdate}>Update Product Listings</button>
With this setup, your product listing page updates almost instantly whenever new products are added or edited, giving users the best of both worlds: speed and freshness.
Developer Perspective: How the Updates Change Your Workflow
The updates in Next.js 15 make ISR more flexible and developer-friendly. Here’s how they impact your code:
- Time-Based to Event-Driven: You’re no longer limited to periodic revalidation. You can now revalidate pages dynamically, making your code more responsive to changes.
- Reduced Build Complexity: With optimized cache invalidation, you don’t need to worry about unintended side effects when regenerating pages.
- API-First Approach: The revalidation API aligns well with modern event-driven architectures, allowing for seamless integration with webhooks and other real-time systems.
When to Use ISR
ISR is ideal for scenarios where content needs to stay fresh but doesn’t require real-time updates, such as:
- E-commerce platforms (e.g., product listings and categories)
- Blogs or news sites
- Marketing pages with frequent updates
Conclusion
Incremental Static Regeneration in Next.js 15 is a game-changer for developers building scalable, high-performance applications. By combining the benefits of static generation with the flexibility of on-demand updates, ISR helps you deliver the best possible experience to your users.
Whether you’re building an e-commerce site, a blog, or a marketing platform, the new features in Next.js 15 make it easier than ever to keep your content fresh without sacrificing speed or scalability.
Top comments (0)