// Get cookies function
function getCookie(name)
{
  var re = new RegExp(name + "=([^;]+)");
  var value = re.exec(document.cookie);
  return (value != null) ? unescape(value[1]) : null;
}

// Listen to changed cookie function
var cookieRegistry = [];

function listenCookieChange(name, callback) {
  setInterval(function() {
    if (cookieRegistry[name]) {
      if (getCookie(name) != cookieRegistry[name]) {
        // update registry so we dont get triggered again
        cookieRegistry[name] = getCookie(name);
        return callback();
      }
    } else {
      cookieRegistry[name] = getCookie(name);
    }
  }, 100);
}

console.log(document.cookie);