JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.1/themes/smoothness/jquery-ui.css">
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.1/jquery-ui.min.js"></script>
<input>

CSS

.special span {
    color: red !important; /* should only apply to may 6 and 8 */
}
.not-special span {
    color: green !important; 
}

JavaScript

var disabledDates = [
    '2015-05-06',
    '2015-05-08'
];

$('input').datepicker({
    minDate: '4/30/2015',
    maxDate: '10/1/2015',
    beforeShowDay: function(date){
         var str = jQuery.datepicker.formatDate('yy-mm-dd', date);
         var minDateArr = $(this).datepicker( "option", "minDate" ).split('/')
        
        var minDate = new Date(minDateArr[2],minDateArr[0]-1,minDateArr[1]);
        if ($.inArray(str, disabledDates) != -1){
            return  [false, 'special']
        }
        else if(date < minDate ){
             return [false, 'not-special']
        }
        else{
            return [true,"special"];
        }
    }
});