TweenLite slideToggle behaviour using scrollHeight attribute for height calculation

slideToggle.js

/**
 * Prerequisites:
 *   element must be block-level & visible
 *   element must have height: 0
 *   element must have overflow: hidden
 * 
 * Returns true if the element was shown, false if it was hidden
 */
function slideToggle(ul)
{
    if (ul.hasClass('active')) {
        TweenLite.to(ul[0], 0.3, { height: 0, onComplete: function() {
            ul.removeClass('active').css('height', '');
        }});
        return false;
    } else {
        TweenLite.to(ul[0], 0.3, { height: ul.prop('scrollHeight'), onComplete: function() {
            ul.addClass('active');
        }});
        return true;
    }
}