var yourGMT = 3; /* your GMT */
var afterHrs = 18; /* your local time when chat shoul dissappear */
var beforeHrs = 10; /* your local time when chat should be back */
yourGMT = -yourGMT*3600000;
afterHrs = afterHrs*3600000 + yourGMT;
beforeHrs = beforeHrs*3600000 + yourGMT;
var currentDate = new Date();
var m = currentDate.getTime() + 60000*currentDate.getTimezoneOffset();
function disableChatEvening(data) {
  var e = new Date(data),
      currentMs = data - e.setHours(0,0,0,0);
  if ((currentMs<beforeHrs)||(currentMs>afterHrs)) {
    carrotquest.removeChat();
  }
};
disableChatEvening(m);