Assets used in HTML template elements are not bundled correctly

[A-D-E-A]

Describe the bug

Bundling images (and I assume other assets) does not work when they are imported in html template elements.

It works when I write <img src="./my-asset.svg"/> in the body, I can see the asset copied in the distant directory (or inlined) and the source url changed accordingly. But when my <img/> is in a <template> element, the url does not change and the asset is not bundled.

(can reproduce using bun, pnpm and npm, haven't tested yarn)

Reproduction

https://stackblitz.com/edit/vitejs-vite-9jcjwh?file=index.html&terminal=dev

Steps to reproduce

Run npm run build and look at the generated html in dist/index.html.

System Info

In stackblitz:

  System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: ^5.3.5 => 5.3.5

On my local machine:

  System:
    OS: Linux 5.15 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
    Memory: 6.41 GB / 7.61 GB
    Container: Yes
    Shell: 5.9 - /usr/bin/zsh
  Binaries:
    Node: 20.16.0 - ~/.proto/shims/node
    npm: 10.8.2 - ~/.proto/shims/npm
    pnpm: 9.2.0 - ~/.proto/shims/pnpm
    bun: 1.1.20 - ~/.bun/bin/bun
  npmPackages:
    vite: ^5.3.5 => 5.3.5

Used Package Manager

pnpm

Logs

Click to expand!

 vite:config no config file found. +0ms
  vite:config using resolved config: {
  vite:config   root: '/home/projects/vitejs-vite-9jcjwh',
  vite:config   base: '/',
  vite:config   mode: 'production',
  vite:config   configFile: undefined,
  vite:config   logLevel: undefined,
  vite:config   clearScreen: undefined,
  vite:config   build: {
  vite:config     target: [ 'es2020', 'edge88', 'firefox78', 'chrome87', 'safari14' ],
  vite:config     cssTarget: [ 'es2020', 'edge88', 'firefox78', 'chrome87', 'safari14' ],
  vite:config     outDir: 'dist',
  vite:config     assetsDir: 'assets',
  vite:config     assetsInlineLimit: 4096,
  vite:config     cssCodeSplit: true,
  vite:config     sourcemap: false,
  vite:config     rollupOptions: {},
  vite:config     minify: 'esbuild',
  vite:config     terserOptions: {},
  vite:config     write: true,
  vite:config     emptyOutDir: null,
  vite:config     copyPublicDir: true,
  vite:config     manifest: false,
  vite:config     lib: false,
  vite:config     ssr: false,
  vite:config     ssrManifest: false,
  vite:config     ssrEmitAssets: 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     modulePreload: { polyfill: true },
  vite:config     cssMinify: true
  vite:config   },
  vite:config   configFileDependencies: [],
  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   rawBase: '/',
  vite:config   resolve: {
  vite:config     mainFields: [ 'browser', 'module', 'jsnext:main', 'jsnext' ],
  vite:config     conditions: [],
  vite:config     extensions: [
  vite:config       '.mjs',  '.js',
  vite:config       '.mts',  '.ts',
  vite:config       '.jsx',  '.tsx',
  vite:config       '.json'
  vite:config     ],
  vite:config     dedupe: [],
  vite:config     preserveSymlinks: false,
  vite:config     alias: [ [Object], [Object] ]
  vite:config   },
  vite:config   publicDir: '/home/projects/vitejs-vite-9jcjwh/public',
  vite:config   cacheDir: '/home/projects/vitejs-vite-9jcjwh/node_modules/.vite',
  vite:config   command: 'build',
  vite:config   ssr: {
  vite:config     target: 'node',
  vite:config     optimizeDeps: { noDiscovery: true, esbuildOptions: [Object] }
  vite:config   },
  vite:config   isWorker: false,
  vite:config   mainConfig: null,
  vite:config   bundleChain: [],
  vite:config   isProduction: true,
  vite:config   plugins: [
  vite:config     'vite:build-metadata',
  vite:config     'vite:watch-package-data',
  vite:config     'vite:pre-alias',
  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-helper',
  vite:config     'vite:worker',
  vite:config     'vite:asset',
  vite:config     'vite:wasm-fallback',
  vite:config     'vite:define',
  vite:config     'vite:css-post',
  vite:config     'vite:build-html',
  vite:config     'vite:worker-import-meta-url',
  vite:config     'vite:asset-import-meta-url',
  vite:config     'vite:force-systemjs-wrap-complete',
  vite:config     'commonjs',
  vite:config     'vite:data-uri',
  vite:config     'vite:dynamic-import-vars',
  vite:config     'vite:import-glob',
  vite:config     'vite:build-import-analysis',
  vite:config     'vite:esbuild-transpile',
  vite:config     'vite:terser',
  vite:config     'vite:reporter',
  vite:config     'vite:load-fallback'
  vite:config   ],
  vite:config   css: { lightningcss: undefined },
  vite:config   esbuild: { jsxDev: false },
  vite:config   server: {
  vite:config     preTransformRequests: true,
  vite:config     sourcemapIgnoreList: [Function: isInNodeModules$1],
  vite:config     middlewareMode: false,
  vite:config     fs: {
  vite:config       strict: true,
  vite:config       allow: [Array],
  vite:config       deny: [Array],
  vite:config       cachedChecks: undefined
  vite:config     }
  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   envDir: '/home/projects/vitejs-vite-9jcjwh',
  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(1) {
  vite:config     'fnpd_/home/projects/vitejs-vite-9jcjwh' => {
  vite:config       dir: '/home/projects/vitejs-vite-9jcjwh',
  vite:config       data: [Object],
  vite:config       hasSideEffects: [Function: hasSideEffects],
  vite:config       webResolvedImports: {},
  vite:config       nodeResolvedImports: {},
  vite:config       setResolvedCache: [Function: setResolvedCache],
  vite:config       getResolvedCache: [Function: getResolvedCache]
  vite:config     },
  vite:config     set: [Function (anonymous)]
  vite:config   },
  vite:config   createResolver: [Function: createResolver],
  vite:config   optimizeDeps: {
  vite:config     holdUntilCrawlEnd: true,
  vite:config     esbuildOptions: { preserveSymlinks: false }
  vite:config   },
  vite:config   worker: { format: 'iife', plugins: '() => plugins', rollupOptions: {} },
  vite:config   appType: 'spa',
  vite:config   experimental: { importGlobRestoreExtension: false, hmrPartialAccept: false },
  vite:config   getSortedPlugins: [Function: getSortedPlugins],
  vite:config   getSortedPluginHooks: [Function: getSortedPluginHooks]
  vite:config } +21ms
vite v5.3.5 building for production...
✓ 1 modules transformed.
dist/index.html  1.53 kB │ gzip: 0.85 kB
✓ built in 1.76s

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• The provided reproduction is a minimal reproducible example of the bug.

[bolt-new-by-stackblitz]

Start a new pull request in StackBlitz Codeflow.

• vitejs-vite-9jcjwh (Open reproduction)

[log101]

Seems like template nodes' children are not inserted into node.childNodes but node.content.childNodes. As the html parser only traverses node.childNodes (1) template children are skipped. I don't know if this behaviour is intentional.
If not I'd love to contribute.

(1):

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

Lines 172 to 184 in 1061102

	function traverseNodes(
	node: DefaultTreeAdapterMap['node'],
	visitor: (node: DefaultTreeAdapterMap['node']) => void,
	) {
	visitor(node)
	if (
	nodeIsElement(node) ||
	node.nodeName === '#document' ||
	node.nodeName === '#document-fragment'
	) {
	node.childNodes.forEach((childNode) => traverseNodes(childNode, visitor))
	}
	}

[sapphi-red]

@log101 Thank you for digging down. I think it's a bug and not intentional.