jQuery下拉滑动切换导航条基于jquery-1.8.3.min.js制作，鼠标经过一级菜单下拉显示二级菜单，鼠标上下移动可以滑动切换二级菜单。-jQuery drop-down slide switch on the navigation bar jquery-1.8.3.min.js production, mouse through a drop-down menu to display the secondary menu, move the mouse up and down can