function scrollDoor(){ 
} 
scrollDoor.prototype = { 
sd : function(menus,divs,openClass,closeClass){ 
var _this = this; 
if(menus.length != divs.length) 
{ 
alert("菜单层数量和内容层数量不一样!"); 
return false; 
} 
for(var i = 0 ; i < menus.length ; i++) 
{ 
_this.$(menus[i]).value = i; 
_this.$(menus[i]).onmouseover = function(){ 
for(var j = 0 ; j < menus.length ; j++) 
{ 
_this.$(menus[j]).className = closeClass; 
_this.$(divs[j]).style.display = "none"; 
} 
_this.$(menus[this.value]).className = openClass; 
_this.$(divs[this.value]).style.display = "block"; 
} 
} 
}, 
$ : function(oid){ 
if(typeof(oid) == "string") 
return document.getElementById(oid); 
return oid; 
} 
}