title: Determine whether the target of a selector has been formatted as a slider
body: <p>I've tried looking at other questions but none seem to work because they're testing whether the selected object is an HTML element rather than a jQuery-ui object.  In short, I'm looking for the following:</p>
  
  <pre><code>var slider = $("#slider").slider();
  if(slider.????) // return true because jQuery created a slider
      alert("It's a slider!");
  else
      alert("Not a slider.");
  </code></pre>