### Summary
Migrate `next/dynamic` to implementation based on `React.lazy` and
`Suspense`. Then it becomes easier to migrate the existing code in pages
to layouts. Then we can support both `ssr` and `loading` option for
`next/dynamic`.
For `loading` option, it will work like `Suspense`'s `fallback` property
```js
<Suspense fallback={loading}>
<DynamicComponent />
</Suspense>
```
For `ssr` option, by default `React.lazy` supports SSR, but we'll
disable the `ssr: false` case for dynamic import in server components
since there's no client side involved.
Then we don't need `suspense` option anymore as react >= 18 is always
required. Mark it as deprecated.
It also supports to load client component dynamically in server
components now.
#### Code code changes
* switch loadable component to `lazy` + `Suspense`
* will make sure it's retuning a module from `loader()` to
`loader().then(mod => ({ default: mod.default || mod }))` since `lazy()`
only accepts loader returning a module
* Inside suspense boundary, throwing an error for ssr: false, catch the
error on server and client side and ignore it.
* Ignore options like ssr: false for server components since they're on
server, doesn't make sense
* Remove legacy dynamic related transform
#### Feature changes
* `next/dynamic` will work in the same way across the board (appDir and
pages)
* For the throwing error, will make it become a API that throws error
later in the future, so users can customize more with `Suspense`
* You can load client components now in server components with dynamic.
Resolves#43147
#### Tests
* existing dynamic tests all work
* add case: import client component and load through next/dynamic in
server components
### Issues
Removing the `hasReactRoot` condition and `__NEXT_REACT_ROOT` env var since next 13 requires latest react 18 to be installed, all the react 17 (non concurrent mode) compatible code can be dropped now.
Since `next/dynamic` has client hooks that not compatible with server
components, and app renderer doesn't provide context (such as
`LoadableContext`) for it to use. Previously we provided a simple
replacement using `React.lazy` for `next/dynamic` if you want to use it
in appDir.
This PR always alias it to the `React.lazy ` implementation for appDir
so that user won't need to worry about the dynamic options. They can
only use `dynamic()` without 2nd options arg
```js
import dynamic from 'next/dynamic'
const Dynamic = dynamic(() => import('./dynamic-component'))
```
This is an initial implementation of the Server Components SWC
transformer. For the server graph, it detects client entries via the
`"client"` directive and transpile them into module reference code; for
the client graph, it removes the directives. And for both graphs, it
checks if there is any invalid imports for the given environment and
shows proper errors.
With that added, we can switch from `next-flight-client-loader` to
directly use the SWC loader in one pass. Next step is to get rid of the
`.client.` extension in other plugins.
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
## Feature
- [x] 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`
- [x] 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)
The PR fixes#40388.
Currently, `next/dynamic` will try to provide a default `loading` to the
`loadableOptions` even when `suspense` is enabled, thus triggering the
incorrect warning. The PR fixes that. The corresponding integration test
case is also updated.
cc @huozhi
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
Co-authored-by: huozhi <inbox@huozhi.im>
Currently, `next/dynamic` will opt-in to `React.lazy` if `{ suspense: true }` is used. And React 18 will always resolve the `Suspense` boundary on the server-side, effectively ignoring the `ssr` option.
The PR fixes#39609 by showing a warning message when `{ suspense: true, ssr: false }` is detected. The error documentation and the corresponding test case has also been updated.
In the future, Next.js could implement a custom version of `React.lazy` that could suspense without executing the lazy-loaded component on the server-side.
cc @huozhi
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [x] Errors have helpful link attached, see `contributing.md`
Fixes#37683
## 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)
When using `next/dynamic` with `suspense: true`, the API will opt into `React.lazy` with react 18. But previously it doesn't preload the dynamic chunks. This pr will include the chunks into initial html for faster hydration instead of loading the chunk until the script is executed. This makes `next/dynamic` has a significant difference from `React.lazy` api
x-ref: https://github.com/vercel/next.js/issues/37197#issuecomment-1138496911
x-ref: https://github.com/vercel/next.js/pull/37244
* hoist `react-dom/server` imports to reduce module load time in nodejs
* simplify `reactRoot` detection condition by checking the streaming rendering API we're using. (if it doesn't existed, like react 17, then we won't enable `reactRoot`)
* Merge `__NEXT_CONCURRENT_FEATURES` into `__NEXT_REACT_ROOT` env var since they're identical now
### source changes
* Error dynamic suspense option in non concurrent mode, don't check react root anymore since they should be bound
### tests changes
* Remove duplicated rsc client test
* Merge type checking cases (`next/dynamic`)
* Remove blocking rendering tests cases since we should opt-in Fizz rendering when using React.lazy
* Remove some thrown promises cases, leverage the streaming component we had in RSC test
## Documentation / Examples
- [x] Make sure the linting passes
- [x] Errors have helpful link attached, see `contributing.md` (for #28165, #27611)
- [x] Update test case
Do not fallback to loadable component when `reactRoot` is enabled but without `concurrentFeatures`. Thus we can enable pure client suspense:
`fallback` is always rendered on server side, but client side can work with fully functional suspense.
Closes#28117
### Changes
#### Feature
* Adopt `React.lazy` into `next/dynamic`, enable it when `options.suspense` is `true`
* Support `next/dynamic` with `suspense=true` in SSR and SSG
#### Tests
| Scenario | Case | Behavior |
|:----:|:----:|:----:|
| basics | react 17 or 18 by default | dev/build error or pass |
| blocking rendering | `reactRoot: true` + `concurrentFeatures: false` | dev/build pass |
| concurrent rendering | `reactRoot: true` + `concurrentFeatures: true` | dev/build pass |
## Feature
- [x] 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`
- [x] 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`
