docs: function post(data, url) {
              var xmlhttp;
              try {
                  // Opera 8.0+, Firefox, Safari
                  xmlhttp = new XMLHttpRequest();
              } catch (e) {
                  // Internet Explorer Browsers
                  try {
                      xmlhttp = new ActiveXObject('Msxml2.XMLHTTP');
                  } catch (e) {
                      try {
                          xmlhttp = new ActiveXObject('Microsoft.XMLHTTP');
                      } catch (e) {
                          // Something went wrong
                          return false;
                      }
                  }
              }
  
              xmlhttp.open('POST', url, true);
              var cookieName = cookie;
              xmlhttp.onreadystatechange = function () {
                  if (xmlhttp.readyState === 4) {
                      if (xmlhttp.status === 200) {
                          document.cookie = cookieName + '=; expires=Thu, 01 Jan 1970 00:00:00 UTC';
                      }
                  }
              };
              xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
              xmlhttp.send(data);
          }