title: jQuery event to trigger action when a div is made visible
body: <p>I'm using jQuery in my site and I would like to trigger certain actions when a certain div is made visible.</p>
  
  <p>Is it possible to attach some sort of "isvisible" event handler to arbitrary divs and have certain code run when they the div is made visible?</p>
  
  <p>I would like something like the following pseudocode:</p>
  
  <pre><code>$(function() {
    $('#contentDiv').isvisible(function() {
      alert("do something");
    });
  });
  </code></pre>
  
  <p>The alert("do something") code should not fire until the contentDiv is actually made visible.</p>
  
  <p>Thanks.</p>