async function handleRequest(request) {
  // Collect the Referer
  const referer = request.headers.get('Referer');

  // If the Referer is empty, access is denied
  if (!referer) {
    return new Response(null, { status: 403 });
  }
  
  // Set Referer allowlist
  const urlInfo = new URL(request.url);
  const refererRegExp = new RegExp(`^https?:\\/\\/${urlInfo.hostname}\\/t-[0-9a-z]{10}\\/.*`)
  
  // If the Referer is not on the allowlist, access is denied
  if (!refererRegExp.test(referer)) {
    return new Response(null, { status: 403 });
  }

  // Normal request, access EdgeOne node cache or origin-pull
  return fetch(request);
}

addEventListener('fetch', event => {
  // When the function code throws an unhandled exception, the Edge function transmits this request back to the origin
  event.passThroughOnException();
  event.respondWith(handleRequest(event.request));
});