title: Understanding waypoints basics
body: <p>I am trying to use the popular "Waypoints" jQuery library. I've looked at various examples and documentation but I am struggling to grasp how to access the element attached to the waypoint.</p>
  
  <p>To make it clearer I have several sections of the page belonging to the <code>.nudgedown</code> class. I'd like to have them change background color once scrolled to. I am trying to see if anything is working at all by alerting their initial background color with this code:</p>
  
  <pre><code>$(".nudgedown").waypoint(function(){
      alert($(this).css("background-color"));
  });
  </code></pre>
  
  <p>However nothing happens and in the console I get this error: </p>
  
  <blockquote>
    <p>TypeError: b.ownerDocument is undefined</p>
  </blockquote>
  
  <p>What am I doing wrong? Am I missing something conceptually in my approach? Thanks in advance for the help.</p>