HTML/Javascript hjælp

<style type="text/css">
.hidden
{
display:none;
}
.visible
{
display:block;
}

</style>

<script type="text/javascript">
function switchViewable(targetid)
{
var trgt = document.getElementById(targetid);
trgt.className = (trgt.className == 'hidden'? 'visible':'hidden');
}
</script>

<ul>
<li>link1</li>
<li><a href="javascript:switchViewable('sublink1')">link2</a></li>
<ul class="hidden" id="sublink1">
<li>sublink1</li>
<li>sublink2</li>
</ul>
<li>link3</
</ul>