this has nothing to do with mandrake ... it is purely an html/javascript issue

to have a javascript execute, you need to have script tags around it ... like this:

<script type="text/javascript">
alert("Hello World");
</script>

Many suggest including a comment around the actual javascript thus:
<script type="text/javascript">
<!--
alert("Hello World");
// -->
</script>

Note that this has two //'s at the beginning of the last line so it is a javascript comment inside an html comment.

If you have your problematic page on the net, posting the url is helpful.