JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://code.jquery.com/mobile/1.0b1/jquery.mobile-1.0b1.js"></script>
<link rel="stylesheet" href="http://code.jquery.com/mobile/1.0b1/jquery.mobile-1.0b1.css">
<div id="page" data-role="page">
<select name="flag" id="flag" data-role="slider">
  <option value="off">OFF</option>
  <option value="on" selected="selected">ON</option>
</select>
</div>

JavaScript

var val = 'on';
$('select#flag').change(function() {
    if(val!==$(this).val()){
        alert($(this).val());
    }
    val = $(this).val();
});