Enabling Partial Prerendering (PPR) for an entire application is
ideally, the goal for teams wanting to test out the feature or adopt it
in their applications to get ready for when it becomes the default
rendering pattern. For large applications, with many routes the new
behaviours of old API's may prove a difficult pill to swallow all at
once.
This aims to enable incremental adoption of PPR for pages and routes
that want to support it in a similar way to how existing segment-level
configurations. Segments can now add:
```ts
export const experimental_ppr = true
```
To enable PPR for that segment and those descending segments. Any subset
of those routes that have it enabled can add:
```ts
export const experimental_ppr = false
```
<details>
<summary>An aside on the choice of <code>experimental_ppr</code>
name</summary>
<blockquote>
<p>It is against common JS semantics to use snake-case, and preference
is given to camel-case instead. The choice to make this snake-case was
to re-enforce that this is an experimental feature, an ugly incremental
path, and ideally, developers should aim to remove all references of it
from their codebase.</p>
<p>Additionally, this mirrors what we've done for unstable API's like
`unstable_cache`.</p>
</blockquote>
</details>
To disable PPR for that segment and those descending segments. To use
this new option, the `experimental.ppr` configuration in
`next.config.js` must be set to `"incremental"`:
```js
// next.config.js
module.exports = {
experimental: {
ppr: "incremental",
},
}
```
If a segment does not export a `experimental_ppr` boolean, it is
inferred from it's parent. If no parent has it defined, it's default
value is `false` and therefore disabled.
Once all your segments have PPR enabled via this config, it would be
considered safe for teams to set their `experimental.ppr` value in the
`next.config.js` to `true`, enabling it for the entire app and for all
future routes.
### Aside
I also took the liberty to rename `isPPR` and `supportsPPR` to be the
clearer `isAppPPREnabled` and `isRoutePPREnabled`.
---------
Co-authored-by: Hendrik Liebau <mail@hendrik-liebau.de>
cdb415451a