how do i open up javascript menu as it was in previous page

[jasonc]

I have a menu that lists all the categories and sub categories, when someone clicks a main category it opens up the sub cats for it. if someone clicks one of the sub cats the page open up to show all items in that category.

But what I would like to find out is how do I get the menu to open up as it was so it shows the category and sub category open?

			  <!-- start show cat list -->
			  			  <br><div style="font-weight: bold; font-size: 0.825em; padding: 0em 0em 0.3125em;">Select items by category</div>
			  <ul class="catMenuItem">
	<li><a style="background-image: url(&quot;images/triangle_down.gif&quot;);" href="#" class="titleTriangle"><span>cat1</span></a></li>
		<li style="display: block;" class="catSubMenu">
			<a href="?cat=2">sub 1-2</a> (0)<br>
			<a href="?cat=7">sub 1-3</a> (2)<br>
			<a href="?cat=8">sub 1-4</a> (0)<br>
			<a href="?cat=9">sub 1-5</a> (0)<br>
			<br>
		</li>
</ul>
<ul class="catMenuItem">
	<li><a href="#" class="titleTriangle"><span>cat2</span></a></li>
		<li style="display: none;" class="catSubMenu">
			<a href="?cat=3">sub 2-1</a> (0)<br>
			<a href="?cat=4">sub 2-2</a> (0)<br>
			<a href="?cat=5">sub 2-3</a> (0)<br>
			<a href="?cat=6">sub 2-4</a> (1)<br>
			<br>
		</li>
</ul>
<ul class="catMenuItem">
	<li><a href="#" class="titleTriangle"><span>cat3</span></a></li>
		<li style="display: none;" class="catSubMenu">
			<br>
		</li>
</ul>
<ul class="catMenuItem">
	<li><a href="#" class="titleTriangle"><span>cat4</span></a></li>
		<li style="display: none;" class="catSubMenu">
			<br>
		</li>
</ul>
<ul class="catMenuItem">
	<li><a href="#" class="titleTriangle"><span>cat5</span></a></li>
		<li style="display: none;" class="catSubMenu">
			<br>
		</li>
</ul>
<script type="text/javascript"><!--
/*		Categories Menu START	*/
    var prevCat;

    function menu(newCat) {
		var mens;
		var anchors;
        if (prevCat) {
			mens = prevCat.parentNode.getElementsByTagName('li')[0];
			anchors = mens.getElementsByTagName('a')[0].style.backgroundImage='url(images/triangle_right.gif)';
			prevCat.style.display = 'none';
		}
		
		if (newCat != prevCat) {
			mens = newCat.parentNode.getElementsByTagName('li')[0];
			anchors = mens.getElementsByTagName('a')[0].style.backgroundImage='url(images/triangle_down.gif)';
			newCat.style.display = 'block';
			prevCat = newCat;
		} else {
			prevCat = null;
		}
		
    }

    onload = function() {
        var menus = document.getElementsByTagName('ul');
        for (var a=0,x=menus.length; a<x; a++) {
            if (menus[a].className === 'catMenuItem') {
                menus[a].getElementsByTagName('li')[0].getElementsByTagName('a')[0].onclick = function() {
                    menu(this.parentNode.parentNode.getElementsByTagName('li')[1]);
                }
                menus[a].getElementsByTagName('li')[1].style.display = 'none';
            }
        }
    } 

/*		Categories Menu END		*/
--></script>
			  <!-- end show cat list -->