Conditional Response

This example returns a response based on the URL of the incoming request, HTTP method, User Agent, IP address, or country of origin of the request.

addEventListener("fetch", (event) => {
    event.respondWith(handleRequest(event.request));
});


async function handleRequest(request) {
  const BLOCKED_HOSTNAMES = ["nope.mywebsite.com", "bye.website.com"];
  // Return a new Response based on a URL's hostname
  const url = new URL(request.url);
  if (BLOCKED_HOSTNAMES.includes(url.hostname)) {
    return new Response("Blocked Host", { status: 403 });
  }
  // Block paths ending in .doc or .xml based on the URL's file extension
  const forbiddenExtRegExp = new RegExp(/\.(doc|xml)$/);
  if (forbiddenExtRegExp.test(url.pathname)) {
    return new Response("Blocked Extension", { status: 403 });
  }
  // On HTTP method
  if (request.method === "POST") {
    return new Response("Response for POST");
  }
  // On User Agent
  const userAgent = request.headers.get("User-Agent") || "";
  if (userAgent.includes("bot")) {
    return new Response("Block User Agent containing bot", { status: 403 });
  }
  // On Client's IP address
  const clientIP = request.headers.get("X-Real-IP");
  if (clientIP === "1.2.3.4") {
    return new Response("Block the IP 1.2.3.4", { status: 403 });
  }

  // On Country
  const country = request.headers.get("X-Country-Code");
  if (country === "CN") {
      return new Response("Block  Request from China", { status: 403 });
  }

  console.error(
    "Getting Client's IP address, device type, and ASN are not supported in playground. Must test on a live worker"
  );
  return fetch(request);
}