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Advanced 20 min readModule: Module 4: Data Fetching, Caching & Revalidation

Incremental Static Regeneration (ISR) & Caching

Master Next.js cache layers: Request Memoization, Data Cache, Full Route Cache, and on-demand revalidation.

What You Will Learn in This Lesson

  • Time-based revalidation (next: { revalidate: 3600 })
  • On-demand cache purging with revalidateTag('courses')
  • Dynamic rendering (export const dynamic = 'force-dynamic')

Introduction & Core Concept

Next.js provides a multi-layer caching system that combines the speed of static HTML with the freshness of real-time database updates.
WHY DOES THIS MATTER IN THE REAL WORLD?

ISR allows a page with 1,000,000 views to be served from CDN cache in 10ms, while refreshing in the background when database content updates.

Data Fetching with ISR Caching

typescript
typescript
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export async function getCourses() {
  const res = await fetch("https://api.kwas.dev/courses", {
    next: { revalidate: 300, tags: ["courses"] }, // Revalidate every 5 minutes
  });
  return res.json();
}

Line-by-Line Technical Breakdown

1revalidatePath('/courses') purges the Full Route Cache on the server instantly.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[TYPESCRIPT]
TYPESCRIPT SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Tag your fetch requests for granular on-demand cache invalidation.

Lesson Summary & Core Takeaways

  • Next.js caching delivers sub-millisecond global CDN speeds with dynamic data freshness.