<script type="text/javascript" src="/js/jquery.js"></script>
<li class="foo">list item 1</li>
<li class="bar">list item 3</li>
<li class="foo">list item 1</li>
<li class="bar">list item 3</li>
<script>$('ul.first').find('.foo').css('background-color', 'red')
.end().find('.bar').css('background-color', 'green');</script>