var openMenu = {};

$(document).ready(function() {
  $('menu > ul > li > a').click(function(event) {
    var element = $(this).siblings()[0];
    
    // ensure we found the element
    if(!element)
      return;
    
    // menus expanded because the user is viewing a page beneath
    // the menu item, shouldn't be opened or closed by clicks
    if(element.className.indexOf('expanded') != -1)
      return;
    else
      event.preventDefault();
    
    // toggle the menu display
    if(openMenu[this.id]) {
      $(element).slideUp();
      openMenu[this.id] = false;
    } else {
      $(element).slideDown();
      openMenu[this.id] = true;
    }
  });
});