feat(nuxt): add page:view-transition:start hook (#26045)

docs/3.api/6.advanced/1.hooks.md

@@ -28,6 +28,7 @@ Hook                   | Arguments           | Environment     | Description
 `page:loading:start`   | -                   | Client          | Called when the `setup()` of the new page is running.
 `page:loading:end`     | -                   | Client          | Called after `page:finish`
 `page:transition:finish`| `pageComponent?`    | Client          | After page transition [onAfterLeave](https://vuejs.org/guide/built-ins/transition.html#javascript-hooks) event.
+`page:view-transition:start` | `transition`        | Client          | Called after `document.startViewTransition` is called when [experimental viewTransition support is enabled](https://nuxt.com/docs/getting-started/transitions#view-transitions-api-experimental).
 
 ## Nuxt Hooks (build time)
 

packages/nuxt/src/app/nuxt.ts

@@ -18,6 +18,7 @@ import type { NuxtError } from '../app/composables/error'
 import type { AsyncDataRequestStatus } from '../app/composables/asyncData'
 import type { NuxtAppManifestMeta } from '../app/composables/manifest'
 import type { LoadingIndicator } from '../app/composables/loading-indicator'
+import type { ViewTransition } from './plugins/view-transitions.client'
 
 import type { NuxtAppLiterals } from '#app'
 
@@ -45,6 +46,7 @@ export interface RuntimeNuxtHooks {
   'page:finish': (Component?: VNode) => HookResult
   'page:transition:start': () => HookResult
   'page:transition:finish': (Component?: VNode) => HookResult
+  'page:view-transition:start': (transition: ViewTransition) => HookResult
   'page:loading:start': () => HookResult
   'page:loading:end': () => HookResult
   'vue:setup': () => void

packages/nuxt/src/app/plugins/view-transitions.client.ts

@@ -14,7 +14,7 @@ export default defineNuxtPlugin((nuxtApp) => {
 
   const router = useRouter()
 
-  router.beforeResolve((to, from) => {
+  router.beforeResolve(async (to, from) => {
     const viewTransitionMode = to.meta.viewTransition ?? defaultViewTransition
     const prefersReducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches
     const prefersNoTransition = prefersReducedMotion && viewTransitionMode !== 'always'
@@ -41,6 +41,8 @@ export default defineNuxtPlugin((nuxtApp) => {
       finishTransition = undefined
     })
 
+    await nuxtApp.callHook('page:view-transition:start', transition)
+
     return ready
   })
 
@@ -55,12 +57,14 @@ export default defineNuxtPlugin((nuxtApp) => {
   })
 })
 
-declare global {
-  interface Document {
-    startViewTransition?: (callback: () => Promise<void> | void) => {
+export interface ViewTransition {
+  ready: Promise<void>
   finished: Promise<void>
   updateCallbackDone: Promise<void>
-      ready: Promise<void>
-    }
+}
+
+declare global {
+  interface Document {
+    startViewTransition?: (callback: () => Promise<void> | void) => ViewTransition
   }
 }