Setting Cookies

// cookie name
const COOKIE_NAME = 'count';

async function handleRequest(request) {
  // collected the current requests' Cookies and resolution into scope
  const cookies = new Cookies(request.headers.get('cookie'));
  const cookieCount = cookies.get(COOKIE_NAME);
  // count increment
  const count = Number(cookieCount && cookieCount.value || 0) + 1;
  // update Cookie's count
  cookies.set(COOKIE_NAME, String(count));

  const response = new Response(`The count is: ${count}`);
  // setting responded cookies
  response.headers.set('Set-Cookie', getSetCookie(cookies.get(COOKIE_NAME)));
  return response;
}

// concatenate Set-Cookie
function getSetCookie(cookie) {
  const cookieArr = [
    `${encodeURIComponent(cookie.name)}=${encodeURIComponent(cookie.value)}`,
  ]; 

  const key2name = {
    expires: 'Expires',
    max_age: 'Max-Age',
    domain: 'Domain',
    path: 'Path',
    secure: 'Secure',
    httponly: 'HttpOnly',
    samesite: 'SameSite',
  };

  Object.keys(key2name).forEach(key => {
    if (cookie[key]) {
      cookieArr.push(`${key2name[key]}=${cookie[key]}`);
    }
  });

  return cookieArr.join('; ');
}

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