feat: node worker support out of the box

docs/config/worker-options.md

@@ -4,10 +4,10 @@ Unless noted, the options in this section are applied to all dev, build, and pre
 
 ## worker.format
 
-- **Type:** `'es' | 'iife'`
+- **Type:** `'es' | 'iife' | 'cjs'`
 - **Default:** `'iife'`
 
-Output format for worker bundle.
+Output format for worker bundle. When using [`?nodeWorker`](/guide/features#node-worker-imports), prefer `'es'` or `'cjs'`. Other formats will be coerced to `'cjs'` for Node worker builds.
 
 ## worker.plugins
 

docs/guide/features.md

@@ -765,6 +765,23 @@ import 'vite/client'
 import MyWorker from './worker?worker&url'
 ```
 
+#### Node Worker Imports
+
+When targeting Node.js worker threads, append the `?nodeWorker` query. The default export is a factory that returns a [`Worker`](https://nodejs.org/api/worker_threads.html#class-worker) from `node:worker_threads`, so it can be used directly in server-side code during development and after build:
+
+```ts twoslash
+import createNodeWorker from './worker?nodeWorker'
+
+const worker = createNodeWorker()
+worker.postMessage('ping')
+worker.on('message', (value) => {
+  console.log(value)
+  worker.terminate()
+})
+```
+
+The same modifiers as web workers are supported. For example, `?nodeWorker&inline` inlines the worker source and runs it with `eval: true`. Node workers currently support `worker.format` values of `'es'` and `'cjs'`; when another format is configured Vite will fall back to `'cjs'`.
+
 See [Worker Options](/config/worker-options.md) for details on configuring the bundling of all workers.
 
 ## Content Security Policy (CSP)

packages/vite/client.d.ts

@@ -221,6 +221,20 @@ declare module '*?worker&url' {
   export default src
 }
 
+declare module '*?nodeWorker' {
+  const workerFactory: (
+    options?: import('node:worker_threads').WorkerOptions,
+  ) => import('node:worker_threads').Worker
+  export default workerFactory
+}
+
+declare module '*?nodeWorker&inline' {
+  const workerFactory: (
+    options?: import('node:worker_threads').WorkerOptions,
+  ) => import('node:worker_threads').Worker
+  export default workerFactory
+}
+
 declare module '*?sharedworker' {
   const sharedWorkerConstructor: {
     new (options?: { name?: string }): SharedWorker

packages/vite/src/node/config.ts

@@ -436,7 +436,7 @@ export interface UserConfig extends DefaultEnvironmentOptions {
      * Output format for worker bundle
      * @default 'iife'
      */
-    format?: 'es' | 'iife'
+    format?: 'es' | 'iife' | 'cjs'
     /**
      * Vite plugins that apply to worker bundle. The plugins returned by this function
      * should be new instances every time it is called, because they are used for each
@@ -536,7 +536,7 @@ export interface LegacyOptions {
 }
 
 export interface ResolvedWorkerOptions {
-  format: 'es' | 'iife'
+  format: 'es' | 'iife' | 'cjs'
   plugins: (bundleChain: string[]) => Promise<ResolvedConfig>
   rollupOptions: RollupOptions
 }
@@ -1437,6 +1437,7 @@ export async function resolveConfig(
     const workerResolved: ResolvedConfig = {
       ...workerConfig,
       ...resolved,
+      command: 'build',
       isWorker: true,
       mainConfig: resolved,
       bundleChain,

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

@@ -257,6 +257,9 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
       const environment = this.environment as DevEnvironment
       const ssr = environment.config.consumer === 'server'
       const moduleGraph = environment.moduleGraph
+      if (!moduleGraph) {
+        return source
+      }
 
       if (canSkipImportAnalysis(importer)) {
         debug?.(colors.dim(`[skipped] ${prettifyUrl(importer, root)}`))