If a checkbox isn't checked, do something
<p>Having some trouble figuring this one out. If both the checkbox in the second and third <code>td</code> is unchecked, then disable the one in the fourth.</p>

<pre><code>$('#allergies tbody tr').each(function () {
  if ($('td:eq(1) input[type="checkbox"]:not(:checked)', $(this)).length &gt; 0 
      &amp;&amp; $('td:eq(2) input[type="checkbox"]:not(:checked)', $(this)).length &gt; 0) {
      $("td:eq(3) input", $(this)).attr('disabled', false);
  }
});
</code></pre>
