Page data HMR (#3132)
Based on #2968
This builds upon #2968 and @ForsakenHarmony's work on data routes to
enable page data HMR.
Page data HMR is a bit more clever than it is in Next.js as we won't
re-render a Node.js result for each page file update. Instead, thanks to
the `StripPageDefaultExport` transform, there are three versions of the
page chunks:
* client-side (strips page data exports);
* server-side (full);
* data server-side (strips page default export).
Instead of subscribing to the full server-side result, on hydration, the
client-side page separately subscribes to:
* client-side updates (already the case);
* data server-side updates (new).
This means that updating something that only affects the page component
will only cause a client-side update and **no Node.js re-rendering**,
while updating something that only affects the data will only cause a
server-side update.
~~I'm marking this as a draft for now as there are still a few areas to
test/investigate:~~
- [x] When something that is used in both the default page export and
data exports is changed, this will cause *two* HMR updates: one data
update, and one client-side chunk update. **The same case breaks in
Next.js, where we will receive a client-side update, but no server-side
update, ending up with an incorrect result.**
- [x] Differences between `getStaticProps/getServerSideProps`, as well
as `getInitialProps` (need to talk with @timneutkens about this) (see
https://github.com/vercel/next.js/pull/44523)
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
