下拉菜单出不来，期待大家指点

CodeBeginner 2005-05-17 01:11:08

menu.js内容如下：
if (document.all) {n=0;ie=1;fShow="visible";fHide="hidden";}
if (document.layers) {n=1;ie=0;fShow="show"; fHide="hide";}

window.onerror=new Function("return true")
rightX = 0;
function Menu()
{
this.bgColor = "#008080";
if (ie) this.menuFont = "bold xx-small Verdana";
if (n) this.menuFont = "bold x-small Verdana";
this.fontColor = "white";
this.addItem = addItem;
this.addSubItem = addSubItem;
this.showMenu = showMenu;
this.mainPaneBorder = 0;
this.subMenuPaneBorder = 0;
this.subMenuPaneWidth = 150;
lastMenu = null;

rightY = 0;
leftY = 0;
leftX = 0;

HTMLstr = "";
HTMLstr += "\n";
HTMLstr += "\n";
if (ie) HTMLstr += "<div id='MainTable' style='position:relative'>\n";

HTMLstr += "<table width='100%' bgcolor='"+this.bgColor+"' border='"+this.mainPaneBorder+"'>\n";
HTMLstr += "<tr>";
HTMLstr += "\n";
HTMLstr += "\n";
HTMLstr += "\n";
HTMLstr += "</tr>\n";
HTMLstr += "</table>\n";
HTMLstr += "\n";
HTMLstr += "\n";
HTMLstr += "\n";
HTMLstr += "\n";
HTMLstr += "\n";
if (ie) HTMLstr+= "</div>\n";
HTMLstr += "\n";
}

function addItem(idItem, text, hint, mlocation, altLocation)
{
var Lookup = "";
if (HTMLstr.indexOf(Lookup) != -1)
{
alert(idParent + " already exist");
return;
}
var MENUitem = "";
MENUitem += "\n\n";
if (ie)
{
MENUitem += "<td>\n";
MENUitem += "<div id='"+idItem+"' style='position:relative; font: "+this.menuFont+";'>\n";
MENUitem += "<a ";
MENUitem += "class=clsMenuItemIE ";
MENUitem += "style='text-decoration: none; font: "+this.menuFont+"; color: "+this.fontColor+"; cursor: hand'";
if (hint != null)
MENUitem += "title='"+hint+"'";
if (mlocation != null)
{
MENUitem += "href='"+mlocation+"'";
MENUitem += "onmouseover=\"hideAll()\" "; //\"为转义字符
}
else
{
if (altLocation != null)
MENUitem += "href='"+altLocation+"'";
else
MENUitem += "href='.' ";
MENUitem += "onmouseover=\"displaySubMenu('"+idItem+"')\" ";
MENUitem += "onclick=\"return false;\" ";
}
MENUitem += ">";
MENUitem += "| \n";
MENUitem += text;
MENUitem += "</a>\n";
MENUitem += "</div>\n";
MENUitem += "</td>\n";
}
MENUitem += "\n\n";
MENUitem += "\n";

HTMLstr = HTMLstr.replace("\n", MENUitem);
}

function addSubItem(idParent, text, hint, mlocation)
{
var MENUitem = "";
Lookup = "";
if (HTMLstr.indexOf(Lookup) == -1)
{
alert(idParent + " not found");
return;
}
Lookup = "";
if (HTMLstr.indexOf(Lookup) == -1)
{
if (ie)
{
MENUitem += "\n";
MENUitem += "<div id='"+idParent+"submenu' style='position:absolute; visibility: hidden; width: "+this.subMenuPaneWidth+"; font: "+this.menuFont+"; top: -300;'>\n";
//MENUitem += "<div id='"+idParent+"submenu' style='position:absolute; visibility: hidden; width: "+this.subMenuPaneWidth+"; font: "+this.menuFont+"; top: 0;'>\n";
MENUitem += "<table border='"+this.subMenuPaneBorder+"' bgcolor='"+this.bgColor+"' width="+this.subMenuPaneWidth+">\n";
MENUitem += "\n";
MENUitem += "</table>\n";
MENUitem += "</div>\n";
MENUitem += "\n";
}
MENUitem += "\n";
HTMLstr = HTMLstr.replace("\n", MENUitem);
}

Lookup = "\n";
if (ie) MENUitem = "<tr><td><a class=clsMenuItemIE title='"+hint+"' href='"+mlocation+"'>"+text+"</a><br></td></tr>\n";
MENUitem += Lookup;
HTMLstr = HTMLstr.replace(Lookup, MENUitem);

}

function showMenu()
{
document.writeln(HTMLstr);
}

function displaySubMenu(idMainMenu)
{
var menu;
var submenu;
if (ie) {
menu = eval(idMainMenu);
submenu = eval(idMainMenu+"submenu.style");
submenu.left = calculateSumOffset(menu, 'offsetLeft');
submenu.top = calculateSumOffset(menu, 'offsetTop') + 30;
submenu.visibility = fShow;

//1.看了整段代码，觉得lastmenu取值只有null或submenu,那这句代码什么时候起作用？
if (lastMenu != null && lastMenu != submenu) hideAll();

leftX = document.all[idMainMenu+"submenu"].style.posLeft;
rightX = leftX + document.all[idMainMenu+"submenu"].offsetWidth;

leftY = document.all[idMainMenu+"submenu"].style.posTop+
document.all[idMainMenu+"submenu"].offsetHeight;
rightY = leftY;
}
lastMenu = submenu;
}

function hideAll()
{
if (lastMenu != null) {lastMenu.visibility = fHide;lastMenu.left = 0;}
}

function calculateSumOffset(idItem, offsetName)
{
var totalOffset = 0;
var item = eval('idItem');
do
{
totalOffset += eval('item.'+offsetName);
item = eval('item.offsetParent');
} while (item != null);//2 .item什么时候为null?或是这个函数的工作机理是什么
return totalOffset;

}

function updateIt(e)
{
if (ie)
{
var x = window.event.clientX;
var y = window.event.clientY;

if (x > rightX || x < leftX) hideAll();
else if (y > rightY) hideAll();
}
}

if (document.all)
{
document.body.onclick=hideAll;
document.body.onscroll=hideAll;
document.body.onmousemove=updateIt;
}
menucontent.js内容如下：
function showMenubar()
{
menu = new Menu();
menu.addItem("User", "会员管理", "会员帐户管理", null, null);
menu.addSubItem("User", "查询/编辑帐户", "查询、修改、删除会员帐户", "edituser.asp");

menu.showMenu();
}

admin.asp（调用文件）内容如下：
<html>
<head>
<title>后台管理</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>

<body bgcolor="#FFFFFF" text="#000000">
<script language="JavaScript" src="menu.js">
</script>
<script language="JavaScript" src="menucontent.js">
</script>
<script language="JavaScript" >
showMenubar();
</script>
<script language="JavaScript">
function UpdateIt(){
if (document.all){
document.all["MainTable"].style.top = document.body.scrollTop;
setTimeout("UpdateIt()", 200);
}
}
UpdateIt();
</script>
</body>
</html>

internet选项->高级->禁止脚本调试（复选框已经没有选中）
问题是在iis中浏览时，菜单没有出现，也没有什么错误提示，该如何调试或是问题出在哪里？
还有注释中的问题1和2，
想了好久都不知所措，期待诸位提点。
源代码改编自下载的

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