$(document).ready(function(){
      var timezone = "Europe/Istanbul";
      $.getJSON("http://json-time.appspot.com/time.json?tz="+timezone+"&callback=?",
        function(data){
           if (data.hour < 12) {
              alert ("Good morning in "+timezone);
          } else {
            alert ("Good afternoon in "+timezone);
          }
        });
      });

stackoverflow