JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://davidwalsh.name/dw-content/jquery-ui-css/custom-theme/jquery-ui-1.7.2.custom.css">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/jquery-ui.min.js"></script>
<input type="text" name="datep" id="datep" readonly="readonly" size="12" />

JavaScript

var availableDates = ["9-5-2017", "14-5-2017", "15-5-2017"];

function check_available(datep) {
 dmy = datep.getDate() + "-" + (datep.getMonth()+1) + "-" + datep.getFullYear();
  console.log(dmy+' : '+($.inArray(dmy, availableDates)));
  if ($.inArray(dmy, availableDates) != -1) {
    return [false, " ","Not Available"];
  } else {
    return [true," ","Available"];
  }
}

$('#datep').datepicker({
  beforeShowDay: check_available
});