Selecting and traversing revisited

To kick off this more in-depth look into selectors and traversing, we'll build a script that will provide yet more selecting and traversing examples to inspect. For our sample, we'll build an HTML document containing a list of news items. We'll place those items in a table so that we can experiment with selecting rows and columns in several ways:

<div id="topics">
  Topics:
  <a href="topics/all.html" class="selected">All</a>
  <a href="topics/community.html">Community</a>
  <a href="topics/conferences.html">Conferences</a>
  <!-- continued... -->
</div>
<table id="news">
  <thead>
    <tr>
      <th>Date</th>
      <th>Headline</th>
      <th>Author</th>
      <th>Topic</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <th colspan="4">2011</th>
    </tr>
    <tr>
      <td>Apr 15&lt...