I have the following Nav:

<li id="categories">
    <ul>
        <li class="cat-item cat-item-8 current-cat"><a href="#">Link</a>
            <ul>
                <li class="cat-item"><a href="#">Link</a></li>
                <li class="cat-item"><a href="#">Link</a></li>
                <li class="cat-item"><a href="#">Link</a></li>
                <li class="cat-item"><a href="#">Link</a></li>
            </ul>
        </li>
        <li class="cat-item cat-item-10"><a href="#">Link</a>
            <ul>
                <li class="cat-item"><a href="#">Link</a></li>
                <li class="cat-item"><a href="#">Link</a></li>
                <li class="cat-item"><a href="#">Link</a></li>
                <li class="cat-item"><a href="#">Link</a>
                    <ul>
                        <li class="cat-item"><a href="#">Link</a></li>
                        <li class="cat-item"><a href="#">Link</a></li>
                        <li class="cat-item"><a href="#">Link</a></li>
                        <li class="cat-item"><a href="#">Link</a></li>
                    </ul>
                </li>
            </ul>
        </li>
    </ul>
</li>

and the following JS:

jQuery("#categories li.cat-item").each(function(){
    var item = jQuery("<span>").addClass('plus'),
        that = jQuery(this);

    if ( that.has("ul").length ) {   
        item.click(function(e){
            var self = jQuery(this);
            self.text( self.text() === "+" ? "-" : "+" )
                .parent().next().toggle();
            e.preventDefault();
        }).text('+');

        that.find(".children").hide();
    }

    that.children("a").prepend( item );
});

This builds a nice toggle menu for my categories. However what I want it to do is based on what category I am currently viewing show the corresponding menu to be opened when the user lands on the page.

Thanks.