### Experimental
Introduce `next/vitals` and `useExperimentalWebVitalsReport` API which is not limited by `_app`.
`pages/index.js`
```jsx
import { useExperimentalWebVitalsReport } from 'next/vitals'
export default function Index() {
useExperimentalWebVitalsReport((metric) => {
// handle metric...
})
return 'sup'
}
```
Send can result in `false` when it did not send the result so we have to fall back in that case. Shared by @timer after my PR was landed.
## 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
Also ensures that even if the navigator.sendBeacon fails the fetch fallback is used.
Fixes#23856. This is likely, as no reproduction was provided it was not possible to verify if it actually fixes the issue.
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
## 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.
## Documentation / Examples
- [ ] Make sure the linting passes
This adds ncc inlining optimizations for the following dependencies:
* cacache
* schema-utils
* find-cache-dir
* mkdirp
* neo-async
* web-vitals
The slight increase in output in the reports here is due to the variation of the bundled version of web-vitals.
In addition, this moves ast-types to be a devDependencies entry instead of in dependencies as it was before https://github.com/vercel/next.js/pull/14746 as I could not see any production usage (ping @prateekbh). Happy to separate that out into a separate PR if preferred too.
This PR adjust the Web Vitals reporting to be called *after* rendering occurs. It used to work like this, but React's render method is no longer synchronous—so we have to do it in an effect.
Existing tests should cover this code path, and IMO it's unfeasible to test that it's invoked _after_ hydration.
Also removed the `&& ST` condition which is not relevant to Web Vitals.