title: Loop every alternate column in table in jQuery
body: <p>Is there a way to loop through every alternate column in a table?</p>
  
  <p>I would like to loop through the TDs of a table but only those that are in columns <code>2, 4, 6 and 8</code>. </p>
  
  <p>I could also add a class to the <code>THs</code> or <code>COLs</code> of these columns if that helps. </p>
  
  <p>I am looking for something like the following (just to demonstrate): </p>
  
  <pre><code>$('#my table tbody (col2,col4,col6,col8)').each(function() {
      $('td').each(function() {
          //do stuff
      });
  });
  </code></pre>