javascript - Add minutes to while loop -

i trying make users end time add 30 mintues on , on over , display time

 function() {              var totime = new date(result2);              while (true) {                  var totime30 = new date(totime.gettime() + totime.gettimezoneoffset() *30 * 1000);                 var totime60 = new date(totime30.gettime() + 30 * 60 * 1000);                  var addmin = totime30 + "" + totime60;                       alert(addmin);                     break;              } 

right code adds first ex 02:00 02:30 how keeps adding 30 minutes time?

update

  var totime = new date(result2);              while (true) {                  var icount = 0;                 var totime30 = new date(totime.gettime() + totime.gettimezoneoffset() *30 * 1000);                 var totime60 = new date(totime30.gettime() + 30 * 60 * 1000);                  var addmin = totime30 + "" + totime60 + (++icount);                   alert(addmin);                 break;             } 

you cannot use variable before initialization. should like

var icount = 0; var t = new date(); var totime30 = new date(t.gettime() + t.gettimezoneoffset() * 30 * 1000); console.log(t.gettime() + " - " + totime30.gettime() + " - " +  (icount++));  .> "1417509086906 - 1417505486906 - 0"