就是这段代码问题.

<SCRIPT type=text/javascript>
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;
 }
}
window.onload = function(){
 var SDmodel = new scrollDoor();
 SDmodel.sd(["m05","m06","m07","m08"],["c05","c06","c07","c08"],"sd05","sd06");
 SDmodel.sd(["m01","m02"],["c01","c02"],"jobsd01","jobsd02");
 SDmodel.sd(["m03","m04"],["c03","c04"],"jobsd01","jobsd02");
}
</SCRIPT>

把错误一起贴出来就有人回话了，呵呵，帮你顶！