Cloudflare worker CORS proxy

proxy.js

// forked from: https://github.com/chebyrash/cors
addEventListener("fetch", event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  try {
    const url = new URL(request.url);

    if (url.pathname === "/") {
      return new Response(`{"usage": "${url.origin}/<url>"}`);
    }

    function addHeaders(response) {
      response.headers.set("Access-Control-Allow-Origin", "*");
      response.headers.set("Access-Control-Allow-Credentials", "true");
      response.headers.set("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
      response.headers.set("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization");
    }
    
    let response;
    if (request.method == "OPTIONS") {
      response = new Response("");
      addHeaders(response);
      return response;
    }

    response = await fetch(request.url.slice(url.origin.length + 1), {
        method: request.method,
        headers: request.headers,
        redirect: "follow",
        body: request.body
    });
    response = new Response(response.body, response)
    addHeaders(response);
    return response;
  } catch (e) {
    return new Response(e.stack || e, {status: 500});
  }
}