Trying to get the calendar working

gistfile1.js

		function startCalendar() {
			$.getJSON(
				'<?= $this->Html->url(array('controller' => 'shifts', 'action' => 'listShifts.json')); ?>', 
				{id: $('<?=$userData?>').val()}, 
				function(json) {
					shiftDays = json;
					$("#datepicker<?=$calendarId?>").datepicker({ 
						beforeShowDay: shiftsWorking, 
						dateFormat: 'yy-mm-dd',
						onSelect: calendarSelect
					});
				}
			);
		}
		
		function shiftsWorking(date) {
		    for (i = 0; i < shiftDays.shiftList.length; i++) {
			  console.log(i);
		      dateDB = new Date(shiftDays.shiftList[i].Shift.date);
		      if (date.getYear() == dateDB.getYear()
		          && date.getMonth() == dateDB.getMonth()
		          && date.getDate() == dateDB.getDate() + 1) {
		        return [true, shiftDays.shiftList[i].Shift.date + '_day'];
		      }
		    }
		  return [false, ''];
		}