title: jQuery - How to add a class to a td tag
body: <p>How would i go about adding a class to a td tag given the following table:</p>
  
  <pre><code>&lt;table&gt;
      &lt;tr&gt;
          &lt;td id="1"&gt;&lt;/td&gt;
          &lt;td id="2"&gt;&lt;/td&gt;
          &lt;td id="3"&gt;&lt;/td&gt;
      &lt;/tr&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>I would like to add the class to the td with the id of 2.  The class name in my case is td_highlight.</p>
  
  <p>Have tried a few different scripts with no luck.</p>
  
  <p>Thanks in advance,
  Billy</p>