fix: allow prerender if no pages specified (#4632)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: radiosilence

docs/start/framework/react/static-prerendering.md

@@ -7,19 +7,32 @@ Static prerendering is the process of generating static HTML files for your appl
 
 ## Prerendering
 
-TanStack Start can prerender your application to static HTML files, which can then be served to users without having to generate them on the fly. To prerender your application, you can add the `server.prerender` option to your `app.config.js` file:
+TanStack Start can prerender your application to static HTML files, which can then be served to users without having to generate them on the fly. To prerender your application, you can add the `prerender` option to your tanstackStart configuration in `vite.config.ts` file:
 
-```js
-// app.config.js
+```ts
+// vite.config.ts
 
-import { defineConfig } from '@tanstack/react-start/config'
+import { tanstackStart } from '@tanstack/react-start/plugin/vite'
 
 export default defineConfig({
-  server: {
-    prerender: {
-      routes: ['/'],
-      crawlLinks: true,
-    },
-  },
+  plugins: [
+    tanstackStart({
+      prerender: {
+        // Enable prerendering
+        enabled: true,
+      },
+      // Optional configuration for specific pages—without this, it will still automatically
+      // prerender all pages
+      pages: [
+        {
+          path: '/my-page',
+          // By default, html files will be named the the same as their route, so `my-page.tsx` would become
+          // `/my-page.html`. However, in order to have a URL path like `/my-page`, it should be an index
+          // inside a directory like so:
+          prerender: { enabled: true, outputPath: '/my-page/index.html' },
+        },
+      ],
+    }),
+  ],
 })
 ```

packages/start-plugin-core/src/nitro-plugin/plugin.ts

@@ -132,12 +132,15 @@ async function buildNitroApp(
 
   // If the user has not set a prerender option, we need to set it to true
   // if the pages array is not empty and has sub options requiring for prerendering
+  // If the user has explicitly set prerender.enabled, this should be respected
   if (options.prerender?.enabled !== false) {
     options.prerender = {
       ...options.prerender,
-      enabled: options.pages.some((d) =>
-        typeof d === 'string' ? false : !!d.prerender?.enabled,
-      ),
+      enabled:
+        options.prerender?.enabled ??
+        options.pages.some((d) =>
+          typeof d === 'string' ? false : !!d.prerender?.enabled,
+        ),
     }
   }