How to disable dates before today in jquery UI datepicker?

I am making a hotel reservation system i have to disable past dates in jQuery UI datepicker here's the code

calling in .cs

   public class CheckLookup
        {
            [DataType(DataType.Date)]
            public DateTime checkindate { get; set; }
            [DataType(DataType.Date)]
            public DateTime checkoutdate { get; set; }
        }

Here's the javascript

 $(document).ready(function () {
        function getDateYymmdd(value) {
            if (value == null)
                return null;
            return $.datepicker.parseDate("yy-mm-dd", value);
        }
        $('.date').each(function () {
            var minDdate = getDateYymmdd($(this).data(""));
            var maxDate = getDateYymmdd($(this).data("val-rangedate-max"));
            $(this).datepicker({
                dateFormat: "dd-mm-yy", 
                minDate: minDate,
                maxDate: maxDate
            });
        });
    });

tell me the modification to be done in this code.