Is the Page Stale?
Easy · Caching
With Incremental Static Regeneration (ISR), a page can export const revalidate = 60: the generated page is reused, and once it is older than 60 seconds Next.js generates a fresh version in the background. revalidate = false means the page is cached forever, and revalidate = 0 means it is never cached (rendered on every request).
Write isStale(generatedAt, now, revalidate). generatedAt and now are timestamps in **milliseconds**; revalidate is in **seconds** or false.
- false: never stale
- 0: always stale
- a number: stale when **more than** revalidate seconds have passed since generatedAt
Simplified model of the real cache.