For use with Cloudflare Worker - detects region and sets a cookie

detectRegionAndSetCookie.js

// For use with a Cloudflare Worker
addEventListener('fetch', event => {
    event.respondWith(fetchAndApply(event.request));
  });
  
async function fetchAndApply(request) {
  // Only run if cookie not present.
  let cookies = request.headers.get('Cookie') || "";

  if (cookies.includes("aam=true")) {
    console.log("AAM not set")
    return fetch(request);
  }

  // Set country and cookie value
  let country = request.headers.get('cf-ipcountry');
  const aamValue = (country === "AU") ? "aam=true" : "aam=false";

  // Set cookie and  return response
  let response = await fetch(request);

  // Make the headers mutable by re-constructing the Response.
  response = new Response(response.body, response);

  response.headers.set('Set-Cookie', aamValue);

  console.log('AAM set');

  return response;
}