Preload code not passing through rollup

Describe the bug

I added a rollup plugin to vite config, but it turned out that it does not affect the preload code. The bundle has mixed code - passed through rollup and not passed through rollup. Could you make preload code go through rollup too?

See the bundle:

dist/assets/index.02199377.js

// this code is not passed through rollup. const is not converted to var by rollup/babel plugin
const p = function polyfill() {
  const relList = document.createElement("link").relList;
  if (relList && relList.supports && relList.supports("modulepreload")) {
    return;
  }
  for (const link of document.querySelectorAll('link[rel="modulepreload"]')) {
    processPreload(link);
  }
  new MutationObserver((mutations) => {
    for (const mutation of mutations) {
      if (mutation.type !== "childList") {
        continue;
      }
      for (const node of mutation.addedNodes) {
        if (node.tagName === "LINK" && node.rel === "modulepreload")
          processPreload(node);
      }
    }
  }).observe(document, { childList: true, subtree: true });
  function getFetchOpts(script) {
    const fetchOpts = {};
    if (script.integrity)
      fetchOpts.integrity = script.integrity;
    if (script.referrerpolicy)
      fetchOpts.referrerPolicy = script.referrerpolicy;
    if (script.crossorigin === "use-credentials")
      fetchOpts.credentials = "include";
    else if (script.crossorigin === "anonymous")
      fetchOpts.credentials = "omit";
    else
      fetchOpts.credentials = "same-origin";
    return fetchOpts;
  }
  function processPreload(link) {
    if (link.ep)
      return;
    link.ep = true;
    const fetchOpts = getFetchOpts(link);
    fetch(link.href, fetchOpts);
  }
};
p();
var style = "";

// this code is passed through rollup. const is converted to var by rollup/babel plugin
var html = "<h1>Hello Vite!</h1>";
document.querySelector("#app").innerHTML = html;

Additional: If this issue will resolved, then this pull request is no longer needed.

Reproduction

see my repo here

npm create vite@latest
√ Select a framework: » vanilla
√ Select a variant: » vanilla
cd <vite project>
pnpm install

• add babel dependencies
• add babelrc config
• add vite config
• add rollup babel to the vite config

vite build --debug

• see the dist/assets/index.[hash].js file

System Info

System:
    OS: Windows 10 10.0.19042
    CPU: (8) x64 Intel(R) Core(TM) i7-3610QM CPU @ 2.30GHz
    Memory: 5.14 GB / 15.89 GB
  Binaries:
    Node: 16.15.1 - E:\Program Files\nodejs\node.EXE
    Yarn: 1.22.19 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 8.11.0 - E:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.1023.0), Chromium (103.0.1264.49)
    Internet Explorer: 11.0.19041.906
  npmPackages:
    vite: ^2.9.9 => 2.9.14

Used Package Manager

pnpm

Logs

Logs

C:\Users\Admin\AppData\Roaming\npm\pnpm.cmd run build

> vite-issues@0.0.0 build D:\projects\-temp\vite\vite-issues
> vite build --debug

  vite:config native esm config loaded in 261.08ms URL {
  href: 'file:///D:/projects/-temp/vite/vite-issues/vite.config.mjs',
  origin: 'null',
  protocol: 'file:',
  username: '',
  password: '',
  host: '',
  hostname: '',
  port: '',
  pathname: '/D:/projects/-temp/vite/vite-issues/vite.config.mjs',
  search: '',
  searchParams: URLSearchParams {},
  hash: ''
} +0ms
  vite:config using resolved config: {
  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: { plugins: [Array] },
  vite:config     minify: false,
  vite:config     terserOptions: {
  vite:config       module: true,
  vite:config       ecma: 5,
  vite:config       safari10: true,
  vite:config       mangle: false,
  vite:config       format: [Object]
  vite:config     },
  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   plugins: [
  vite:config     'vite:build-metadata',
  vite:config     'alias',
  vite:config     'vite:modulepreload-polyfill',
  vite:config     'vite:resolve',
  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-babel',
  vite:config     'vite:define',
  vite:config     'vite:css-post',
  vite:config     'vite:build-html',
  vite:config     'vite:worker-import-meta-url',
  vite:config     'vite:watch-package-data',
  vite:config     'commonjs',
  vite:config     'vite:data-uri',
  vite:config     'rollup-plugin-dynamic-import-variables',
  vite:config     'vite:asset-import-meta-url',
  vite:config     'babel',
  vite:config     'vite:build-import-analysis',
  vite:config     'vite:esbuild-transpile',
  vite:config     'vite:reporter',
  vite:config     'vite:load-fallback'
  vite:config   ],
  vite:config   configFile: 'D:/projects/-temp/vite/vite-issues/vite.config.mjs',
  vite:config   configFileDependencies: [ 'D:/projects/-temp/vite/vite-issues/vite.config.mjs' ],
  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     build: {}
  vite:config   },
  vite:config   root: 'D:/projects/-temp/vite/vite-issues',
  vite:config   base: '/',
  vite:config   resolve: { dedupe: undefined, alias: [ [Object], [Object] ] },
  vite:config   publicDir: 'D:\\projects\\-temp\\vite\\vite-issues\\public',
  vite:config   cacheDir: 'D:\\projects\\-temp\\vite\\vite-issues\\node_modules\\.vite',
  vite:config   command: 'build',
  vite:config   mode: 'production',
  vite:config   isWorker: false,
  vite:config   isProduction: true,
  vite:config   server: {
  vite:config     preTransformRequests: true,
  vite:config     fs: { strict: true, allow: [Array], deny: [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: 'production', DEV: false, PROD: true },
  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) { set: [Function (anonymous)] },
  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], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object]
  vite:config     ],
  vite:config     rollupOptions: {}
  vite:config   }
  vite:config } +22ms
build.terserOptions is specified but build.minify is not set to use Terser. Note Vite now defaults to use esbuild for minification. If you still prefer Terser, set build.minify to "
terser".
vite v2.9.14 building for production...
✓ 4 modules transformed.
dist/assets/favicon.17e50649.svg   1.49 KiB
dist/index.html                    0.46 KiB
dist/assets/index.02199377.js      1.38 KiB / gzip: 0.57 KiB
dist/assets/index.38b0c734.css     0.19 KiB / gzip: 0.16 KiB

Process finished with exit code 0

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 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.

[bluwy]

I’ve checked rollup/plugins repo. It seems most of the virtual modules has a extension.

Interesting. I think it’s still risky to expect virtual modules in general to have an extension though, but thanks for the pointer. Maybe we could consider adding extensions for Vite too.

plugin-legacy does transpile the code using babel and skips esbuild transpilation.

You’re right, I forgot that plugin-legacy skips esbuild. In that case babel would be handling syntax transform then via plugin-legacy’s target option.

[sapphi-red]

That’s because plugin-legacy now only injects polyfills. Syntax transformation are handled by esbuild and build.target, down to es2015.

plugin-legacy does transpile the code using babel and skips esbuild transpilation. https://github.com/vitejs/vite/blob/519f7debe176d99f464a96240842c303d8ec5e57/packages/plugin-legacy/src/index.ts#L353-L402 And yes, plugin-legacy does not have an option to control babel finely.