This PR adds a new `experimental.enableUndici` option to let the
developer switch from `next-fetch` to `undici` as the underlying
polyfill for `fetch` in Node.js.
In the current implementation, Next.js makes sure that `fetch` is always
available by using `node-fetch`. However, we do not polyfill in Node.js
18+, since those versions come with their own `fetch` implementation
already, built-in.
Node.js 18+ uses `undici` under the hood, so letting the developer use
`undici` earlier could make the migration easier later on.
Eventually, we hope to be able to stop polyfilling `fetch` in an
upcoming major version of Next.js, shipping less code.
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
Co-authored-by: Balázs Orbán <info@balazsorban.com>
Co-authored-by: Sukka <isukkaw@gmail.com>
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Steven <steven@ceriously.com>
