title: jQuery removeClass() but not certain classes
body: <p>How can I do remove all classes from an element except certain classes. I'm assuming we can't use not with <code>removeClass()</code>. Let say I have a <code>&lt;div class="aa bb cc dd ee ff"&gt;&lt;/div&gt;</code> and I want to remove all classes except <code>aa dd</code>. How can I do this. </p>