datepicker prevent choose day

//MUST ADD:
<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.css" defer />

  <script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"
integrity="sha256-T0Vest3yCU7pafRw9r+settMBX6JkKN06dqBnpQ8d30="
crossorigin="anonymous"></script>

// php (cakephp)

<div class="col-sm-4 col-xs-12">
  <?php echo $this->Form->input('delivery_date', array(
    'class' => 'form-control', 'label' => false, 'placeholder' => __d('frontend', 'select_delivery_date'), 'required')); ?>    </div>
</div>

// java script

function addDays(date, days) {
  var result = new Date(date);
  result.setDate(date.getDate() + days);
  return result;
}


$('#InoviceDeliveryDate').datepicker({
		orientation: 'bottom',
		format: 'yyyy-mm-dd',
		todayBtn: "linked",
		autoclose: true,
		todayHighlight: true,
		maxViewMode: 0,
		beforeShowDay: function(date) {

			startDate = new Date(); 
			endDate = addDays(startDate, 30); // extent 30 days more

			start 		= startDate.getTime();
			end 		= endDate.getTime();
			current 	= date.getTime();

            // prevent choose this date on calendar; 2021/02/12, 2021/02/13, 2021/02/14
			special_dates = [];
			special_dates.push(new Date('2021/02/12').getTime());
			special_dates.push(new Date('2021/02/13').getTime());
			special_dates.push(new Date('2021/02/14').getTime());

			if (start <= current && current <= end) {
				for (var i = 0; i < special_dates.length; i++) {

					console.log(special_dates[i] + " " + current);
					if (current === special_dates[i]) {
						return [ false, "", "unAvailable" ];

					}
				}
				return [ true, "", "Available" ];

			} else {
				return [ false, "", "unAvailable" ];
			}

		},
		//language: 'custom',
	}).on('changeDate', function(e) {
		// `e` here contains the extra attributes
		$('#InoviceDeliveryDate').datepicker('hide');
	});