JSFiddle - React, Tailwind, and code Playground
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.11/themes/base/jquery-ui.css">
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.11/i18n/jquery-ui-i18n.min.js"></script>
<input />
<div id="result"></div>
JavaScript
var dateP = $('input').datepicker();
// dateP language is currently 'zh-TW' (because of jquery-ui-i18n.min.js)
// Change it
dateP.datepicker('option', $.datepicker.regional['fr']);
// => ok
// Change date format
var MyDateFormat = 'D d MM yy';
var res = $.datepicker.formatDate(MyDateFormat , new Date());
$('#result').text(res); // wtf?