title: jQuery do something when select options' values are not empty/NULL
body: <p>Here's a scenario. Supposing I have multiple <code>&lt;select&gt;</code>'s on a page (can be 0,1,2,3,4 or more) and I want some piece of code to fire when the option values are not equal to <code>""</code> or <code>NULL</code>. Is there a quick fire method in jQuery to find this? The selects will be in a <code>&lt;div&gt;</code> tag with class of <code>class="variations"</code> but no useful classes or id's for the selects themselves are present as they will be dynamically generated based on the current page/product id.</p>
  
  <p>I can get it to work when one or the other is not equal to <code>""</code> or NULL but I just can't seem to get it to fire when only both are selected (and then fire again when both are unselected, if that makes sense).</p>