Function devHtmlHook

packages/vite/src/node/server/middlewares/indexHtml.ts:204–449

(
  html,
  { path: htmlPath, filename, server, originalUrl },
)

  return processedUrl
}
const devHtmlHook: IndexHtmlTransformHook = async (
  html,
  { path: htmlPath, filename, server, originalUrl },
) => {
  const { config, watcher } = server!
  const base = config.base || '/'
  const decodedBase = config.decodedBase || '/'

  let proxyModulePath: string
  let proxyModuleUrl: string

  const trailingSlash = htmlPath.endsWith('/')
  if (!trailingSlash && fs.existsSync(filename)) {
    // If htmlPath is a /@fs/ URL (e.g. vitest-browser always uses this form
    // for testerHtmlPath), normalise to an absolute FS path so proxyCacheUrl
    // is always root-relative.
    proxyModulePath = htmlPath.startsWith(FS_PREFIX) ? filename : htmlPath
    proxyModuleUrl = htmlPath
  } else {
    // There are users of vite.transformIndexHtml calling it with url '/'
    // for SSR integrations #7993, filename is root for this case
    // A user may also use a valid name for a virtual html file
    // Mark the path as virtual in both cases so sourcemaps aren't processed
    // and ids are properly handled
    const validPath = `${htmlPath}${trailingSlash ? 'index.html' : ''}`
    proxyModulePath = `\0${validPath}`
    proxyModuleUrl = wrapId(proxyModulePath)
  }
  proxyModuleUrl = joinUrlSegments(decodedBase, proxyModuleUrl)

  const s = new MagicString(html)
  let inlineModuleIndex = -1
  // The key to the proxyHtml cache is decoded, as it will be compared
  // against decoded URLs by the HTML plugins.
  const proxyCacheUrl = decodeURI(
    cleanUrl(proxyModulePath).replace(normalizePath(config.root), ''),
  )
  const styleUrl: AssetNode[] = []
  const inlineStyles: InlineStyleAttribute[] = []
  const inlineModulePaths: string[] = []

  const addInlineModule = (
    node: DefaultTreeAdapterMap['element'],
    ext: 'js',
  ) => {
    inlineModuleIndex++

    const contentNode = node.childNodes[0] as DefaultTreeAdapterMap['textNode']

    const code = contentNode.value

    let map: SourceMapInput | undefined
    if (proxyModulePath[0] !== '\0') {
      map = new MagicString(html)
        .snip(
          contentNode.sourceCodeLocation!.startOffset,
          contentNode.sourceCodeLocation!.endOffset,
        )