title: jQuery addClass removed after reload the content
body: <p>I used </p>
  
  <pre><code>$("select").addClass("dropdown") 
  </code></pre>
  
  <p>to add 'dropdown' class on select box, but when the select box content refresh, above added class removed automatically.</p>
  
  <p>Such as, when I select a country name, state options reloaded and when reloaded above added class is also removed.</p>
  
  <p>How can I add class using jQuery, so it will stay even refreshed?</p>