Function indexHtmlMiddleware

packages/vite/src/node/server/middlewares/indexHtml.ts:451–552

(
  root: string,
  server: ViteDevServer | PreviewServer,
)

}

export function indexHtmlMiddleware(
  root: string,
  server: ViteDevServer | PreviewServer,
): Connect.NextHandleFunction {
  const isDev = isDevServer(server)
  const fullBundle = isDev && server.environments.client.bundledDev

  // Keep the named function. The name is visible in debug logs via `DEBUG=connect:dispatcher ...`
  return async function viteIndexHtmlMiddleware(req, res, next) {
    if (res.writableEnded) {
      return next()
    }

    const url = req.url && cleanUrl(req.url)
    // htmlFallbackMiddleware appends '.html' to URLs
    if (url?.endsWith('.html') && req.headers['sec-fetch-dest'] !== 'script') {
      if (fullBundle) {
        let pathname
        try {
          pathname = decodeURIComponent(url)
        } catch {
          // ignore malformed URI
          return next()
        }
        const filePath = pathname.slice(1) // remove first /

        let file = fullBundle.memoryFiles.get(filePath)
        if (!file && fullBundle.memoryFiles.size !== 0) {
          return next()
        }
        const secFetchDest = req.headers['sec-fetch-dest']
        if (
          [
            'document',
            'iframe',
            'frame',
            'fencedframe',
            '',
            undefined,
          ].includes(secFetchDest) &&
          ((await fullBundle.triggerBundleRegenerationIfStale()) ||
            file === undefined)
        ) {
          file = { source: await generateFallbackHtml(server as ViteDevServer) }
        }
        if (!file) {
          return next()
        }

        const html =
          typeof file.source === 'string'
            ? file.source
            : Buffer.from(file.source)
        const headers = server.config.server.headers
        return send(req, res, html, 'html', { headers, etag: file.etag })
      }

      let filePath: string