feat(nuxt): add prerenderRoutes ssr composable (#22863)

docs/3.api/3.utils/prerender-routes.md

@@ -0,0 +1,20 @@
+---
+description: prerenderRoutes hints to Nitro to prerender an additional route.
+---
+
+# `prerenderRoutes`
+
+When prerendering, you can hint to Nitro to prerender additional paths, even if their URLs do not show up in the HTML of the generated page.
+
+`prerenderRoutes` can only be called within component setup functions, plugins, and route middleware.
+
+```js
+const route = useRoute()
+
+prerenderRoutes('/')
+prerenderRoutes(['/', '/about'])
+```
+
+::alert{icon=👉}
+In the browser, or if called outside prerendering, `prerenderRoutes` will have no effect.
+::

docs/3.api/4.advanced/2.kit.md

@@ -88,7 +88,7 @@ description: Nuxt Kit provides composable utilities to help interacting with Nux
 - `addDevServerHandler (handler)`
 - `useNitro()` (only usable after `ready` hook)
 - `addServerPlugin`
-- `addPrerenderRoutes`
+- `prerenderRoutes`
 
 ### Resolving
 

packages/kit/src/nitro.ts

@@ -45,7 +45,7 @@ export function addServerPlugin (plugin: string) {
 /**
  * Adds routes to be prerendered
  */
-export function addPrerenderRoutes (routes: string | string[]) {
+export function prerenderRoutes (routes: string | string[]) {
   const nuxt = useNuxt()
   if (!Array.isArray(routes)) {
     routes = [routes]

packages/nuxt/src/app/components/nuxt-island.ts

@@ -11,7 +11,7 @@ import type { FetchResponse } from 'ofetch'
 import type { NuxtIslandResponse } from '../../core/runtime/nitro/renderer'
 import { getFragmentHTML, getSlotProps } from './utils'
 import { useNuxtApp, useRuntimeConfig } from '#app/nuxt'
-import { useRequestEvent } from '#app/composables/ssr'
+import { prerenderRoutes, useRequestEvent } from '#app/composables/ssr'
 
 // @ts-expect-error virtual file
 import { remoteComponentIslands } from '#build/nuxt.config.mjs'
@@ -127,7 +127,7 @@ export default defineComponent({
       if (import.meta.server && import.meta.prerender) {
         const hints = r.headers.get('x-nitro-prerender')
         if (hints) {
-          appendResponseHeader(event, 'x-nitro-prerender', hints)
+          prerenderRoutes(hints)
         }
       }
       setPayload(key, result)

packages/nuxt/src/app/composables/index.ts

@@ -23,7 +23,7 @@ export { useFetch, useLazyFetch } from './fetch'
 export type { FetchResult, UseFetchOptions } from './fetch'
 export { useCookie } from './cookie'
 export type { CookieOptions, CookieRef } from './cookie'
-export { useRequestHeaders, useRequestEvent, useRequestFetch, setResponseStatus } from './ssr'
+export { prerenderRoutes, useRequestHeaders, useRequestEvent, useRequestFetch, setResponseStatus } from './ssr'
 export { onNuxtReady } from './ready'
 export { abortNavigation, addRouteMiddleware, defineNuxtRouteMiddleware, onBeforeRouteLeave, onBeforeRouteUpdate, setPageLayout, navigateTo, useRoute, useRouter } from './router'
 export type { AddRouteMiddlewareOptions, RouteMiddleware } from './router'

packages/nuxt/src/app/composables/ssr.ts

@@ -1,5 +1,5 @@
 import type { H3Event } from 'h3'
-import { setResponseStatus as _setResponseStatus, getRequestHeaders } from 'h3'
+import { setResponseStatus as _setResponseStatus, appendHeader, getRequestHeaders } from 'h3'
 import type { NuxtApp } from '../nuxt'
 import { useNuxtApp } from '../nuxt'
 
@@ -35,3 +35,10 @@ export function setResponseStatus (arg1: H3Event | number | undefined, arg2?: nu
   }
   return _setResponseStatus(useRequestEvent(), arg1, arg2 as string | undefined)
 }
+
+export function prerenderRoutes (path: string | string[]) {
+  if (!process.server || !process.env.prerender) { return }
+
+  const paths = Array.isArray(path) ? path : [path]
+  appendHeader(useRequestEvent(), 'x-nitro-prerender', paths.map(p => encodeURIComponent(p)).join(', '))
+}

packages/nuxt/src/imports/presets.ts

@@ -37,6 +37,7 @@ const appPreset = defineUnimportPreset({
     'useRequestURL',
     'setResponseStatus',
     'setPageLayout',
+    'prerenderRoutes',
     'onNuxtReady',
     'useRouter',
     'useRoute',

test/fixtures/basic/components/ServerOnlyComponent.server.vue

@@ -1,7 +1,5 @@
 <script setup>
-import { appendResponseHeader } from 'h3'
+prerenderRoutes(['/some/url/from/server-only/component'])
-
-appendResponseHeader(useRequestEvent(), 'x-nitro-prerender', '/some/url/from/server-only/component')
 </script>
 
 <template>

test/nuxt/composables.test.ts

@@ -47,6 +47,7 @@ describe('composables', () => {
       'getRouteRules',
       'onNuxtReady',
       'setResponseStatus',
+      'prerenderRoutes',
       'useRequestEvent',
       'useRequestFetch',
       'isPrerendered',
@@ -200,6 +201,7 @@ describe('ssr composables', () => {
     expect(useRequestEvent()).toBeUndefined()
     expect(useRequestFetch()).toEqual($fetch)
     expect(useRequestHeaders()).toEqual({})
+    expect(prerenderRoutes('/')).toBeUndefined()
   })
 })