perf(nuxt): use granular watcher to avoid crawling ignored dirs (#20836)

packages/nuxt/src/core/builder.ts

@@ -1,7 +1,8 @@
 import { pathToFileURL } from 'node:url'
 import type { EventType } from '@parcel/watcher'
+import type { FSWatcher } from 'chokidar'
 import chokidar from 'chokidar'
-import { isIgnored, tryResolveModule } from '@nuxt/kit'
+import { isIgnored, tryResolveModule, useNuxt } from '@nuxt/kit'
 import { interopDefault } from 'mlly'
 import { debounce } from 'perfect-debounce'
 import { normalize } from 'pathe'
@@ -55,6 +56,81 @@ const watchEvents: Record<EventType, 'add' | 'addDir' | 'change' | 'unlink' | 'u
 
 async function watch (nuxt: Nuxt) {
   if (nuxt.options.experimental.watcher === 'parcel') {
+    const success = await createParcelWatcher()
+    if (success) { return }
+  }
+
+  if (nuxt.options.experimental.watcher === 'chokidar') {
+    return createWatcher()
+  }
+
+  return createGranularWatcher()
+}
+
+function createWatcher () {
+  const nuxt = useNuxt()
+
+  const watcher = chokidar.watch(nuxt.options._layers.map(i => i.config.srcDir as string).filter(Boolean), {
+    ...nuxt.options.watchers.chokidar,
+    cwd: nuxt.options.srcDir,
+    ignoreInitial: true,
+    ignored: [
+      isIgnored,
+      '.nuxt',
+      'node_modules'
+    ]
+  })
+
+  watcher.on('all', (event, path) => nuxt.callHook('builder:watch', event, normalize(path)))
+  nuxt.hook('close', () => watcher.close())
+}
+
+function createGranularWatcher () {
+  const nuxt = useNuxt()
+
+  if (nuxt.options.debug) {
+    console.time('[nuxt] builder:chokidar:watch')
+  }
+
+  let pending = 0
+
+  const ignoredDirs = new Set([...nuxt.options.modulesDir, nuxt.options.buildDir])
+  const pathsToWatch = nuxt.options._layers.map(layer => layer.config.srcDir).filter(d => d && !isIgnored(d))
+  for (const path of nuxt.options.watch) {
+    if (typeof path !== 'string') { continue }
+    if (pathsToWatch.some(w => path.startsWith(w.replace(/[^/]$/, '$&/')))) { continue }
+    pathsToWatch.push(path)
+  }
+  for (const dir of pathsToWatch) {
+    pending++
+    const watcher = chokidar.watch(dir, { ...nuxt.options.watchers.chokidar, ignoreInitial: false, depth: 0, ignored: [isIgnored] })
+    const watchers: Record<string, FSWatcher> = {}
+
+    watcher.on('all', (event, path) => {
+      if (!pending) {
+        nuxt.callHook('builder:watch', event, normalize(path))
+      }
+      if (event === 'unlinkDir' && path in watchers) {
+        watchers[path].close()
+        delete watchers[path]
+      }
+      if (event === 'addDir' && path !== dir && !ignoredDirs.has(path) && !(path in watchers) && !isIgnored(path)) {
+        watchers[path] = chokidar.watch(path, { ...nuxt.options.watchers.chokidar, ignored: [isIgnored] })
+        watchers[path].on('all', (event, path) => nuxt.callHook('builder:watch', event, normalize(path)))
+        nuxt.hook('close', () => watchers[path].close())
+      }
+    })
+    watcher.on('ready', () => {
+      pending--
+      if (nuxt.options.debug && !pending) {
+        console.timeEnd('[nuxt] builder:chokidar:watch')
+      }
+    })
+  }
+}
+
+async function createParcelWatcher () {
+  const nuxt = useNuxt()
   if (nuxt.options.debug) {
     console.time('[nuxt] builder:parcel:watch')
   }
@@ -83,32 +159,10 @@ async function watch (nuxt: Nuxt) {
         nuxt.hook('close', () => subscription.unsubscribe())
       })
     }
-      return
+    return true
   }
-    console.warn('[nuxt] falling back to `chokidar` as `@parcel/watcher` cannot be resolved in your project.')
-  }
-
-  if (nuxt.options.debug) {
-    console.time('[nuxt] builder:chokidar:watch')
-  }
-
-  const watcher = chokidar.watch(nuxt.options._layers.map(i => i.config.srcDir as string).filter(Boolean), {
-    ...nuxt.options.watchers.chokidar,
-    cwd: nuxt.options.srcDir,
-    ignoreInitial: true,
-    ignored: [
-      isIgnored,
-      '.nuxt',
-      'node_modules'
-    ]
-  })
-
-  if (nuxt.options.debug) {
-    watcher.on('ready', () => console.timeEnd('[nuxt] builder:chokidar:watch'))
-  }
-
-  watcher.on('all', (event, path) => nuxt.callHook('builder:watch', event, normalize(path)))
-  nuxt.hook('close', () => watcher.close())
+  console.warn('[nuxt] falling back to `chokidar-granular` as `@parcel/watcher` cannot be resolved in your project.')
+  return false
 }
 
 async function bundle (nuxt: Nuxt) {

packages/nuxt/src/core/schema.ts

@@ -76,7 +76,7 @@ export default defineNuxtModule({
           }
           return
         }
-        console.warn('[nuxt] falling back to `chokidar` as `@parcel/watcher` cannot be resolved in your project.')
+        console.warn('[nuxt] falling back to `chokidar-granular` as `@parcel/watcher` cannot be resolved in your project.')
       }
 
       const filesToWatch = await Promise.all(nuxt.options._layers.map(layer =>

packages/schema/src/config/common.ts

@@ -358,6 +358,7 @@ export default defineUntypedSchema({
       '.output',
       '.git',
       await get('analyzeDir'),
+      await get('buildDir'),
       await get('ignorePrefix') && `**/${await get('ignorePrefix')}*.*`
     ].concat(val).filter(Boolean)
   },

packages/schema/src/config/experimental.ts

@@ -161,15 +161,19 @@ export default defineUntypedSchema({
     /**
      * Set an alternative watcher that will be used as the watching service for Nuxt.
      *
-     * Nuxt uses 'chokidar' by default, but by setting this to `parcel` it will use
-     * `@parcel/watcher` instead. This may improve performance in large projects or
-     * on Windows platforms.
+     * Nuxt uses 'chokidar-granular' by default, which will ignore top-level directories
+     * (like `node_modules` and `.git`) that are excluded from watching.
+     *
+     * You can set this instead to `parcel` to use `@parcel/watcher`, which may improve
+     * performance in large projects or on Windows platforms.
+     *
+     * You can also set this to `chokidar` to watch all files in your source directory.
      *
      * @see https://github.com/paulmillr/chokidar
      * @see https://github.com/parcel-bundler/watcher
      * @default chokidar
-     * @type {'chokidar' | 'parcel'}
+     * @type {'chokidar' | 'parcel' | 'chokidar-granular'}
      */
-    watcher: 'chokidar'
+    watcher: 'chokidar-granular'
   }
 })