while converting local time to utc , time is not correct

 var convertLocalTimeToUTC = function() {
var date = new Date();
          var utc = date.getTime();
          var offset = (date.getTimezoneOffset() /60);
          var newdate = new Date(utc + (3600000 * offset));
          var finaldate = newdate.toLocaleString();
          alert(finaldate);
}