function menuclick( submenu ,cellbar)
{
if( old_menu != submenu ){
if( old_menu !='' ){
old_menu.style.display = 'none';
old_cell.src= 'photo/plus.gif';
}
submenu.style.display = 'block';
cellbar.src = 'photo/plus2.gif';
old_menu = submenu;
old_cell = cellbar;
}else{
submenu.style.display = 'none';
cellbar.src= 'photo/plus.gif';
old_menu = '';
old_cell = '';
}
}有高手能具体解释一下上面的每行代码吗，菜鸟求问啊
{
if( old_menu != submenu ){
if( old_menu !='' ){
old_menu.style.display = 'none';
old_cell.src= 'photo/plus.gif';
}
submenu.style.display = 'block';
cellbar.src = 'photo/plus2.gif';
old_menu = submenu;
old_cell = cellbar;
}else{
submenu.style.display = 'none';
cellbar.src= 'photo/plus.gif';
old_menu = '';
old_cell = '';
}
}有高手能具体解释一下上面的每行代码吗，菜鸟求问啊
{
if( old_menu != submenu ){ //当前点击的菜单是否等于上次点击的菜单
if( old_menu !='' ){ //如果上次有点击菜单的话
old_menu.style.display = 'none'; //这行与下行都是对上次点击菜单的样式处理，应该是样式还原
old_cell.src= 'photo/plus.gif';
}
submenu.style.display = 'block'; //这行与下行都是对本次点击菜单的样式处理
cellbar.src = 'photo/plus2.gif';
old_menu = submenu; //这次点的菜单置为“上次点击菜单”，供下次点击菜单是使用
old_cell = cellbar;
}else{ //如果本次点击的菜单与上次点击的菜单相同
submenu.style.display = 'none'; //样式还原
cellbar.src= 'photo/plus.gif';
old_menu = ''; //“上次点击菜单”置空
old_cell = '';
}
}