URL rewrite based on regular expressions

async function handleEvent(event) {
  const { request } = event;
  const urlInfo = new URL(request.url);
  // Regular expression matches /test/ followed by 1 or 2 path segments that are not slashes
  const regexp = /^\/test\/([^\/]+)(?:\/([^\/]+))?\/?$/;
  // Check if the path matches the regular expression
  if (regexp.test(urlInfo.pathname)) {
    const matches = urlInfo.pathname.match(regexp);
    let newPathname = '/test/';
    // Construct a new pathname, which may be one or two according to the number of matched path segments
    newPathname += matches[1]; // The first path segment
    if (matches[2]) {
      newPathname += '/' + matches[2]; // The second path segment, if any
    }
    // Ensure it ends with index.html
    newPathname += '/index.html';
    // Update the pathname of URLInfo
    urlInfo.pathname = newPathname;
  }
  
  // Make a request using the updated URLInfo
  const response = await fetch(urlInfo.toString(), {
    method: request.method,
    headers: request.headers,
    redirect: 'manual',
    body: request.body,
  });
  // return the response to the event
  return event.respondWith(response);
}

// call the handleEvent function for each fetch event
addEventListener('fetch', (event) => {
  handleEvent(event);
});