Add experimental support for history.pushState and history.replaceState (#58335)
## What?
This PR introduces support for manually calling `history.pushState` and `history.replaceState`.
It's currently under an experimental flag:
```js
/**
* @type {import('next').NextConfig}
*/
const nextConfig = {
experimental: {
windowHistorySupport: true,
},
}
module.exports = nextConfig
```
Going forward I'll refer to `history.pushState` as `replaceState` is interchangable.
When the flag is enabled you're able to call the web platform `history.pushState` in the usual way:
```js
const data = {
foo: 'bar'
}
const url = '/my-new-url?search=tim'
window.history.pushState(data, '', url)
```
Let's start by explaining what would happen without the flag:
When a new history entry is pushed outside of the Next.js router any back navigation to that history entry will cause a browser reload as it can no longer be used by Next.js as the required metadata for the router is missing. In practice this makes it so that pushState/replaceState is not feasible to be used. Any pathname / searchParams added can't be observed by `usePathname` / `useSearchParams` either.
With the flag enabled the pushState/replaceState calls are instrumented and is synced into the Next.js router. This way the Next.js router's internal metadata is preserved, making back navigations apply still, and pathname / searchParams is synced as well, making sure that you can observe it using `usePathname` and `useSearchParams`.
## How?
- Added a new experimental flag `windowHistorySupport`
- Instruments `history.pushState` and `history.replaceState`
- Triggers the same action as popstate (ACTION_RESTORE) to sync the provided url (if provided) into the Next.js router
- Copies the Next.js values kept in history.state so that they are not lost
- Calls the original pushState/replaceState
~~Something to figure out is how we handle additional pushes/replaces in Next.js as that should override the history state that was previously set.~~
Went with this after discussing with @sebmarkbage:
- When you open a page it preserves the custom history state
- This is to solve this case: when you manually `window.history.pushState` / `window.history.replaceState` and then do an mpa navigation (i.e. `<a>` or `window.location.href`) and the navigate backwards the custom history state is preserved
- When you navigate back and forward (popstate) it preserves the custom history state
- When you navigate client-side (i.e. `router.push()` / `<Link>`) the custom history state is not preserved
next.js
797fecb0 - Add experimental support for history.pushState and history.replaceState (#58335)
