Why this does not work in firefox i try to select the category and then make subcategory visible.

<script type=text/javascript>

    function show_sub(cat) {

      var cat = document.getElementById(cat);

      var sub = cat.getElementsByName(sub);

      sub[0].style.display='inline'; 

}



</script>

-

<ul>

    <li id=cat onclick=show_sub(this)>

        Top 1

        <ul style=display:none name=sub>

            <li>Sub 1</li>

            <li>Sub 2</li>

            <li>Sub 3</li>

        </ul>

    </li>

    <li>Top 2</li>

    <li>Top 3</li>

    <li>Top 4</li>

</ul>

EDIT Answer is:

<script type=text/javascript>

   function show_sub(cat) {

      cat.getElementsByTagName(ul)[0].style.display = (cat.getElementsByTagName(ul)[0].style.display == none) ? inline : none;

   }

</script>