title: $(document).scrollTop() always returns 0
body: <p>I'm simply trying to do something once the scroll position of the page reaches a certain height. However <code>scrollTop()</code> is returning 0 or <code>null</code> no matter how far down I scroll. This is the help function I'm using to check the <code>scrollTop()</code> value: </p>
  
  <pre><code>$('body').click(function(){
      var scrollPost = $(document).scrollTop();
      alert(scrollPost);
  });
  </code></pre>
  
  <p>I've tried attaching <code>scrollTop()</code> to <code>$('body')</code>, <code>$('html')</code> and of course <code>$(window)</code>, but nothing changes. </p>
  
  <p>Any ideas?</p>