Currently we error if you cannot produce a shell unless you have a
Suspense boundary above the root. This is fine for normal IO but sync IO
like Math.random() and new Date() have much more significant bad
consequences for prerendering. Instead of treating these errors as
another flavor of "must have a shell" validation we should instead treat
them like they must be guarded behind something else dynamic like `await
connection()`.
In addition to unconditionally erroring for Sync IO in Server Components
when prerendering this change also removes the Sync IO warning for
runtime prefetches. This is because at the moment there is no way to
debug these errors in dev. In the future we will add validation for
prefetches and need to add back in some ability to warn for these cases
but until then we will leave this case as a silent deopt.
When you use sync IO in the client in a way that needs to be fixed we
currently still just provide you with the explanation for server
components. The fixes when sync IO happens in the client are not the
same as when they happen in a server component so this update adds
client specific documentation for these situations.
Namely, the key difference is that on the server you can add caching
through "use cache" and this is not available to you in the client. sync
IO in general is (going to be) allowed in client components broadly as
long as Next.js has a fallback UI to prerender. This means that "fixing"
sync IO access in the client will usually be solved by wrapping in a
Suspense boundary. The alternative is to move the sync IO out of render
or move it to the server where it can be cached.
## Description
Some files use `md` extension.
So, I corrected it by changing the extension to `mdx`.
### Improving Documentation
- [x] Run `pnpm prettier-fix` to fix formatting issues before opening
the PR.
- [x] Read the Docs Contribution Guide to ensure your contribution
follows the docs guidelines:
https://nextjs.org/docs/community/contribution-guide
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Josh Story