Cloudflare Worker as Redirected URL Resolver

worker.js

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

/**
 * Respond to the request
 * @param {Request} request
 * @returns {Response}
 */
async function handleRequest(request) {
  const url = new URL(request.url).searchParams.get("url");

  if (
    request.method === "GET" &&
    url &&
    (url.startsWith("http://") || url.startsWith("https://"))
  ) {
    const response = await fetch(url, { method: "HEAD" });

    return Response.redirect(response.url);
  }

  return new Response("Invalid Request", { status: 400 });
}