JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css">
<div id="event-calender"></div>

JavaScript

jQuery(document).ready(function () {
    var your_dates = [new Date(2016, 6, 27), new Date(2016, 7, 7)];
    
    //var your_dates = ["2016-6-27", "2016-7-7"];
    
    jQuery("div#event-calender").datepicker({
        beforeShowDay: function (date) {
        	
          var curDate = date.getFullYear()+"-"+date.getMonth()+"-"+date.getDay();
          
          console.log(curDate);
          
            var arr = [];
            
            console.log("curDate: "+curDate);
            //console.log("your_dates[0]:"+your_dates[0]);
            for(i = 0; i<your_dates.length;i++){
            		console.log( your_dates[i] );
            }
            //for(i = 0; i<your_dates.length;i++){
               //var dat = $.datepicker.formatDate("yy-mm-dd", d);
               /*if (jQuery.inArray(date.toString(), your_dates) != -1) {
                    console.log("0");
                    arr = [true, 'highlight'];
                }else {
                    console.log("1");
                    arr = [true, ''];
                }
                */
                console.log(your_dates.indexOf(date));
                
                if (your_dates.indexOf(date) != '-1'){
                        arr = [true, 'highlight'];
                        console.log("0");
                    }
                  else {
                        console.log("1");
                        arr = [true, ''];
                  }
            //}
            
            return arr;
        }
    });
});