Creating a Worker inside a plugin doesn't trigger the worker proccessing

Describe the bug

This code

export default new Worker(new URL('./test.js', import.meta.url))

in a file works at it integrates the ./test.js file into the vite build proccess.

But having a plugin wich returns this code at the load hook doesn’t work.

---

The reproduction include is minimal exept for vite-plugin-inspect as it helped me to debug it…

---

There are some use cases for this (just a refrence so you see this would make things more easy):

For example my plugin vite-plugin-comlink uses a custom worker-build setup for this. But I can’t rewrite it with the 2.8 features as I need to create the worker code in a plugin.

Reproduction

https://github.com/mathe42/worker-test

System Info

System:
    OS: Windows 10 10.0.19044
    CPU: (8) x64 AMD FX(tm)-8320 Eight-Core Processor
    Memory: 4.44 GB / 11.96 GB
  Binaries:
    Node: 16.14.2 - ~\AppData\Local\Volta\tools\image\node\16.14.2\node.EXE
    Yarn: 1.22.18 - ~\AppData\Local\Volta\tools\image\yarn\1.22.18\bin\yarn.CMD
    npm: 8.5.0 - ~\AppData\Local\Volta\tools\image\node\16.14.2\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.1266.0), Chromium (100.0.1185.44)
  npmPackages:
    vite: ^2.9.2 => 2.9.5

Used Package Manager

pnpm

Logs

vite:config bundled config file loaded in 154.22ms +0ms
  vite:config using resolved config: {
  vite:config   plugins: [
  vite:config     'vite:pre-alias',
  vite:config     'alias',
  vite:config     'vite:modulepreload-polyfill',
  vite:config     'vite:resolve',
  vite:config     'vite:optimized-deps',
  vite:config     'vite:html-inline-proxy',
  vite:config     'vite:css',
  vite:config     'vite:esbuild',
  vite:config     'vite:json',
  vite:config     'vite:wasm',
  vite:config     'vite:worker',
  vite:config     'vite:asset',
  vite:config     'vite-plugin-inspect',
  vite:config     'ex',
  vite:config     'vite:define',
  vite:config     'vite:css-post',
  vite:config     'vite:worker-import-meta-url',
  vite:config     'vite:client-inject',
  vite:config     'vite:import-analysis'
  vite:config   ],
  vite:config   server: {
  vite:config     preTransformRequests: true,
  vite:config     fs: { strict: true, allow: [Array], deny: [Array] }
  vite:config   },
  vite:config   configFile: 'C:/Users/Sebastian/worker-test/vite.config.js',
  vite:config   configFileDependencies: [ 'C:/Users/Sebastian/worker-test/vite.config.js' ],
  vite:config   inlineConfig: {
  vite:config     root: undefined,
  vite:config     base: undefined,
  vite:config     mode: undefined,
  vite:config     configFile: undefined,
  vite:config     logLevel: undefined,
  vite:config     clearScreen: undefined,
  vite:config     server: {}
  vite:config   },
  vite:config   root: 'C:/Users/Sebastian/worker-test',
  vite:config   base: '/',
  vite:config   resolve: { dedupe: undefined, alias: [ [Object], [Object] ] },
  vite:config   publicDir: 'C:\\Users\\Sebastian\\worker-test\\public',
  vite:config   cacheDir: 'C:\\Users\\Sebastian\\worker-test\\node_modules\\.vite',
  vite:config   command: 'serve',
  vite:config   mode: 'development',
  vite:config   isWorker: false,
  vite:config   isProduction: false,
  vite:config   build: {
  vite:config     target: [ 'es2019', 'edge88', 'firefox78', 'chrome87', 'safari13.1' ],
  vite:config     polyfillModulePreload: true,
  vite:config     outDir: 'dist',
  vite:config     assetsDir: 'assets',
  vite:config     assetsInlineLimit: 4096,
  vite:config     cssCodeSplit: true,
  vite:config     cssTarget: [ 'es2019', 'edge88', 'firefox78', 'chrome87', 'safari13.1' ],
  vite:config     sourcemap: false,
  vite:config     rollupOptions: {},
  vite:config     minify: 'esbuild',
  vite:config     terserOptions: {},
  vite:config     write: true,
  vite:config     emptyOutDir: null,
  vite:config     manifest: false,
  vite:config     lib: false,
  vite:config     ssr: false,
  vite:config     ssrManifest: false,
  vite:config     reportCompressedSize: true,
  vite:config     chunkSizeWarningLimit: 500,
  vite:config     watch: null,
  vite:config     commonjsOptions: { include: [Array], extensions: [Array] },
  vite:config     dynamicImportVarsOptions: { warnOnError: true, exclude: [Array] }
  vite:config   },
  vite:config   preview: {
  vite:config     port: undefined,
  vite:config     strictPort: undefined,
  vite:config     host: undefined,
  vite:config     https: undefined,
  vite:config     open: undefined,
  vite:config     proxy: undefined,
  vite:config     cors: undefined,
  vite:config     headers: undefined
  vite:config   },
  vite:config   env: { BASE_URL: '/', MODE: 'development', DEV: true, PROD: false },
  vite:config   assetsInclude: [Function: assetsInclude],
  vite:config   logger: {
  vite:config     hasWarned: false,
  vite:config     info: [Function: info],
  vite:config     warn: [Function: warn],
  vite:config     warnOnce: [Function: warnOnce],
  vite:config     error: [Function: error],
  vite:config     clearScreen: [Function: clearScreen],
  vite:config     hasErrorLogged: [Function: hasErrorLogged]
  vite:config   },
  vite:config   packageCache: Map(0) {},
  vite:config   createResolver: [Function: createResolver],
  vite:config   optimizeDeps: {
  vite:config     esbuildOptions: { keepNames: undefined, preserveSymlinks: undefined }
  vite:config   },
  vite:config   worker: {
  vite:config     format: 'iife',
  vite:config     plugins: [
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object]
  vite:config     ],
  vite:config     rollupOptions: {}
  vite:config   }
  vite:config } +14ms

  vite v2.9.5 dev server running at:

  > Local: http://localhost:3000/
  > Network: use `--host` to expose

  ready in 438ms.

  vite:deps scanning for dependencies... { timestamp: true } +0ms
  > Inspect: http://localhost:3000/__inspect/

  vite:deps Crawling dependencies using entries:
  vite:deps   C:/Users/Sebastian/worker-test/index.html +0ms
  vite:time 0.88ms / +0ms
  vite:resolve 1.62ms /main.js -> C:/Users/Sebastian/worker-test/main.js +0ms
  vite:deps Scan completed in 87.96ms: {} +48ms
  vite:deps dependencies found:  { timestamp: true } +91ms
  vite:deps ✨ optimized dependencies unchanged { timestamp: true } +8ms
  vite:resolve 1.88ms C:\Users\Sebastian\worker-test\node_modules\.pnpm\vite@2.9.5\node_modules\vite\dist\client\client.mjs -> C:/Users/Sebastian/worker-test/node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/client.mjs +0ms
  vite:resolve 2.50ms /@vite/client -> C:/Users/Sebastian/worker-test/node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/client.mjs +0ms
  vite:load 3.55ms [fs] /@vite/client +0ms
  vite:resolve 1.78ms C:\Users\Sebastian\worker-test\node_modules\.pnpm\vite@2.9.5\node_modules\vite\dist\client\env.mjs -> C:/Users/Sebastian/worker-test/node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs +26ms
  vite:resolve 2.15ms @vite/env -> C:/Users/Sebastian/worker-test/node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs +0ms
  vite:resolve 1.48ms /node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs -> C:/Users/Sebastian/worker-test/node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs +2ms
  vite:import-analysis 11.46ms [1 imports rewritten] node_modules\.pnpm\vite@2.9.5\node_modules\vite\dist\client\client.mjs +0ms
  vite:transform 19.37ms /@vite/client +0ms
  vite:time 37.38ms /@vite/client +213ms
  vite:load 9.06ms [fs] /node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs +37ms
  vite:import-analysis 0.08ms [no imports] node_modules\.pnpm\vite@2.9.5\node_modules\vite\dist\client\env.mjs +19ms
  vite:transform 1.35ms /node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs +16ms
  vite:time 9.85ms /node_modules/.pnpm/vite@2.9.5/node_modules/vite/dist/client/env.mjs +17ms
The request url "C:/" is outside of Vite serving allow list.

- C:/Users/Sebastian/worker-test

Refer to docs https://vitejs.dev/config/#server-fs-allow for configurations and more details.

  vite:time 4.27ms ..\..\.. +396ms

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn’t already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it’s a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

I got it. import.meta.url was replaced by this feature.

Vite will replace __filename, __dirname, and import.meta.url in CommonJS and TypeScript config files. Using these as variable names will result in an error: https://vitejs.dev/config/#config-file-resolving

This config will work.

import { defineConfig } from 'vite'
import inspect from 'vite-plugin-inspect'

export default defineConfig({
    plugins: [
        inspect(),
        {
            name: 'ex',
            enforce: 'pre',
            resolveId(id) {
                if(id === ':example') return id
            },
            load(id) {
                if(id!==':example') return

                const importMeta = 'import.meta'
                return `
                    export default new Worker(new URL('./test.js', ${importMeta}.url))
                `
            }
        }
    ]
})

But it is a bit confusing. package.json does not have type: module so vite.config.js should be treated as CommonJS. Contrary to it, vite.config.js is written in ESM, it seems it import.meta.url gets replaced.

[mathe42]

Oh yes it works THANKS!