Instruction: Describe what Incremental Static Regeneration (ISR) is and how it works in Next.js.
Context: This question probes the candidate's knowledge of ISR, a key feature in Next.js for improving site performance without sacrificing content freshness.
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Incremental Static Regeneration allows pages to be generated statically on-demand, after the build time. This means that once a user requests a page, if that page was not pre-generated at build time, ISR will generate it statically and cache it for future requests. More importantly, ISR can regenerate pages in the background when the data changes, ensuring users always receive the most current version without any perceivable delay.
Here's how it works in practice: When you deploy a Next.js application, you can specify which pages should use ISR by setting the revalidate property in the page's getStaticProps function. This property tells Next.js how often it should check for updates to the data that generates the page. If the data has changed since the...