feat: optimize deps option to turn off auto discovery

packages/vite/src/node/optimizer/index.ts

@@ -125,6 +125,14 @@ export interface DepOptimizationConfig {
    * @experimental
    */
   disabled?: boolean | 'build' | 'dev'
+  /**
+   * Automatic dependency discovery. When `noDiscovery` is true, only dependencies
+   * listed in `include` will be optimized. The scanner isn't run for cold start
+   * in this case. CJS-only dependencies must be present in `include` during dev.
+   * @default false
+   * @experimental
+   */
+  noDiscovery?: boolean
 }
 
 export type DepOptimizationOptions = DepOptimizationConfig & {

packages/vite/src/node/optimizer/optimizer.ts

@@ -217,7 +217,11 @@ async function createDepsOptimizer(
       newDepsDiscovered = true
     }
 
-    if (!isBuild) {
+    if (config.optimizeDeps.noDiscovery) {
+      // We don't need to scan for dependencies or wait for the static crawl to end
+      // Run the first optimization run immediately
+      runOptimizer()
+    } else if (!isBuild) {
       // Important, the scanner is dev only
       depsOptimizer.scanProcessing = new Promise((resolve) => {
         // Runs in the background in case blocking high priority tasks

packages/vite/src/node/plugins/preAlias.ts

@@ -49,7 +49,9 @@ export function preAliasPlugin(config: ResolvedConfig): Plugin {
           if (optimizedId) {
             return optimizedId // aliased dep already optimized
           }
-
+          if (depsOptimizer.options.noDiscovery) {
+            return
+          }
           const resolved = await this.resolve(id, importer, {
             ...options,
             custom: { ...options.custom, 'vite:pre-alias': true },

packages/vite/src/node/plugins/resolve.ts

@@ -816,6 +816,7 @@ export function tryNodeResolve(
   }
 
   const skipOptimization =
+    depsOptimizer?.options.noDiscovery ||
     !isJsType ||
     (importer && isInNodeModules(importer)) ||
     exclude?.includes(pkgId) ||

playground/optimize-deps-no-discovery/__tests__/optimize-deps.spec.ts

@@ -0,0 +1,17 @@
+import { expect, test } from 'vitest'
+import { isBuild, page, readFile } from '~utils'
+
+test('optimized dep', async () => {
+  expect(await page.textContent('.optimized-dep')).toBe('[success]')
+})
+
+test('vue + vuex', async () => {
+  expect(await page.textContent('.vue')).toMatch(`[success]`)
+})
+
+test.runIf(!isBuild)('metadata', async () => {
+  const meta = await readFile('node_modules/.vite/deps/_metadata.json')
+  expect(meta).toMatch(`"@vitejs/test-dep-no-discovery"`)
+  expect(meta).not.toMatch(`"vue"`)
+  expect(meta).not.toMatch(`"vuex"`)
+})

playground/optimize-deps-no-discovery/dep-no-discovery/index.js

@@ -0,0 +1,2 @@
+// written in cjs, optimization should convert this to esm
+module.exports = '[success]'

playground/optimize-deps-no-discovery/dep-no-discovery/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "@vitejs/test-dep-no-discovery",
+  "private": true,
+  "version": "1.0.0",
+  "main": "index.js"
+}

playground/optimize-deps-no-discovery/index.html

@@ -0,0 +1,24 @@
+<h1>Optimize Deps</h1>
+
+<h2>Optimized Dep</h2>
+<div class="optimized-dep"></div>
+
+<h2>Vue & Vuex</h2>
+<div class="vue"></div>
+
+<script>
+  function text(el, text) {
+    document.querySelector(el).textContent = text
+  }
+</script>
+
+<script type="module">
+  import msg from '@vitejs/test-dep-no-discovery'
+  text('.optimized-dep', msg)
+
+  import { createApp } from 'vue'
+  import { createStore } from 'vuex'
+  if (typeof createApp === 'function' && typeof createStore === 'function') {
+    text('.vue', '[success]')
+  }
+</script>

playground/optimize-deps-no-discovery/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "@vitejs/test-optimize-deps-no-discovery",
+  "private": true,
+  "version": "0.0.0",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "debug": "node --inspect-brk ../../packages/vite/bin/vite",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@vitejs/test-dep-no-discovery": "file:./dep-no-discovery",
+    "vue": "^3.2.47",
+    "vuex": "^4.1.0"
+  }
+}

playground/optimize-deps-no-discovery/vite.config.js

@@ -0,0 +1,21 @@
+import { defineConfig } from 'vite'
+
+// Overriding the NODE_ENV set by vitest
+process.env.NODE_ENV = ''
+
+export default defineConfig({
+  optimizeDeps: {
+    disabled: false,
+    noDiscovery: true,
+    include: ['@vitejs/test-dep-no-discovery'],
+  },
+
+  build: {
+    // to make tests faster
+    minify: false,
+    // Avoid @rollup/plugin-commonjs
+    commonjsOptions: {
+      include: [],
+    },
+  },
+})