Add incremental static regeneration

Overview

One of the best features of Next.js is incremental static regeneration. It would be great to have something similar to it.

https://nextjs.org/docs/basic-features/data-fetching#incremental-static-regeneration

The core features being:

• Pages can be dynamically generated
• Resulting page is cached for X time
• After X time, the page is dynamically regenerated again

In the ideal world, there would also be some way to invalidate the cache. https://github.com/vercel/next.js/discussions/16488

As I understand Sveltekit, currently, this is not possible.

Proposed solution

Extend the prerender API with a revalidate parameter.

<script context="module">
	export const prerender = true;
	export const revalidate = 900; // 900 seconds, or 15 minutes
</script>

[benmccann]

If there aren’t many users then you also don’t need to worry about performance very much

[Conduitry]

This can essentially be done now by returning cache headers and having a proxy sitting in front of the Kit app that understands those cache headers. I’m not entirely convinced this needs its own implementation solely in Kit.