javascript+div+css写的树型下拉菜单不能正常显示（高分求救）

好吧先贴全码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<link href="common/css/navigaleft.css" type="text/css" rel="stylesheet"/>
<script type=text/javascript><![CDATA[//></script>
</head>
<body text="000000" link="0000cc" vlink="0000cc" alink="ff6600" topmargin="0" leftmargin="0" bottommargin="0" rightmargin="0">
<div style="height:10px; background:url(images/lead/lanmushodown.gif); width:960px;"><img src="images/spacer.gif" width="1" height="10" /></div>
</div>
<table width="960" border="0" cellspacing="0" cellpadding="0" align="center">
  <tr>
    <td rowspan="2">
   <div style="width:200px; height:366px; float:left">
    <div style="height:10px; background:url(images/lead/bgt.gif)"><img src="images/spacer.gif" width="1" height="10" /></div>
    <div style="height:366px; background:url(images/lead/bg.gif)" align="center"><div style="width: 160px"><table border="0" cellspacing="0" cellpadding="0" width='100%'>
<tr><td>
<div id="parent">
<ul id="navi">
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu1"  onclick="DoMenu('ChildMenu1')">电子数码<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu1" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=1">手机</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=2">照相机</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=3">MP3</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=4">MP4</a></li>
   <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=5">电脑配件</a></li>
    <li><a href="goodslist.asp?Cateid=8">收音机</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu2" onclick="DoMenu('ChildMenu2')">生活饰品<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu2" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=9">镜子</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=10">枕头</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=11">杯子</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=12">钟表</a></li>
    <li ><a href="goodslist.asp?Cateid=13">台灯</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px;"><a href="#Menu=ChildMenu3" onclick="DoMenu('ChildMenu3')">休闲娱乐<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu3" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=14">玩偶</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=15">盒子</a></li>
    <li><a href="goodslist.asp?Cateid=16">相框</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu4" onclick="DoMenu('ChildMenu4')">个人时尚<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu4" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=17">T恤</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=18">休闲包</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=19">鞋子</a></li>
    <li ><a href="goodslist.asp?Cateid=20">钱包</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu5" onclick="DoMenu('ChildMenu5')">办公愉悦<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu5" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=21">笔</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=22">记事本</a></li>
    </ul>
</li>
</ul>
</div>
</td></tr></table>
</div>
    </div>
    <div style="height:35px; background:url(images/lead/bgb.gif)" align="right"><div style="padding-top:20px"></div>
    </div>
  </div>
    </td>
  </tr>
</table>
</body>
</html>
你的javascript是写在head里的而要调用 body里的对象 html页面解释是从上到下的 head->title->body 也就是说你在head里就调用body里的对象，而这个时候body里的对象还没有创建好所以会报错，而将要执行的语句放在window.onload里就不会了因为是在页面加载完后才调用body里对象所以不会报错！！window.onload={
GetMenuID();
menuFix2();
};这个的意思就是在页面加载完后才调用上边两个函数明白没有？
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style>
#navi {
    width:150px;
    line-height: 24px;
    list-style-type: none;
    text-align:left;
    }
#navi a {
    width: 80px;
    display: block;
    padding-left:20px;
    color:#780a21;
    font-size:14px;
    }
#navi li {
    background:#CCC;
    float:left;
    }
#navi li a:hover{
    background:#FFFFFF;
}
#navi a:link  {
    color:#780a21;
     text-decoration:none;
}
#navi a:visited  {
    color:#780a21;
    text-decoration:none;
}
#navi a:hover  {
    color:#780a21;
    text-decoration:none;
    font-weight:bold;
}
#navi li ul {
    list-style:none;
    text-align:left;
}
#navi li ul li{
    background:#FFFFFF;
}
#navi li ul a{
         padding-left:20px;
         width:100px;
    }
#navi li ul a:link  {
    color:#780a21;
    text-decoration:none;
}
#navi li ul a:visited  {
    color:#780a21;
    text-decoration:none;
}
#navi li ul a:hover {
    color:#780a21;
    text-decoration:none;
    font-weight:bold;
    background-color:#FFFFFF;
}
#navi li:hover ul {
    left: auto;
}
#navi li.sfhover ul {
    left: auto;
}
#content {
    clear: left;
}
#navi ul.collapsed {
    display: none;
}
-->
#parent{
    width:200px;
    padding-left:20px;
}
</style>
<script type=text/javascript>//<![CDATA[//><!--
var LastLeftID = "";
function menuFix2() {
    var obj = document.getElementById("navi").getElementsByTagName("li");
    for (var i=0; i<obj.length; i++) {
        obj[i].onmouseover=function() {
            this.className+=(this.className.length>0? " ": "") + "sfhover";
        }
        obj[i].onMouseDown=function() {
            this.className+=(this.className.length>0? " ": "") + "sfhover";
        }
        obj[i].onMouseUp=function() {
            this.className+=(this.className.length>0? " ": "") + "sfhover";
        }
        obj[i].onmouseout=function() {
            this.className=this.className.replace(new RegExp("( ?|^)sfhover\\b"), "");
        }
    }
}
function DoMenu(emid)
{
    var obj = document.getElementById(emid);
    obj.className = (obj.className.toLowerCase() == "expanded"?"collapsed":"expanded");
    if((LastLeftID!="")&&(emid!=LastLeftID))
    {
        document.getElementById(LastLeftID).className = "collapsed";
    }
    LastLeftID = emid;
}
function GetMenuID()
{    var MenuID="";
    var _paramStr = new String(window.location.href);    var _sharpPos = _paramStr.indexOf("#");
    if (_sharpPos >= 0 && _sharpPos < _paramStr.length - 1)
    {
        _paramStr = _paramStr.substring(_sharpPos + 1, _paramStr.length);
    }
    else
    {
        _paramStr = "";
    }

    if (_paramStr.length > 0)
    {
        var _paramArr = _paramStr.split("&");
        if (_paramArr.length>0)
        {
            var _paramKeyVal = _paramArr[0].split("=");
            if (_paramKeyVal.length>0)
            {
                MenuID = _paramKeyVal[1];
            }
        }
    }
    if(MenuID!="")
    {
        DoMenu(MenuID)
    }
}
window.onload=function()
{
GetMenuID();
menuFix2();
}//]]></script>
</head>
<body text="000000" link="0000cc" vlink="0000cc" alink="ff6600" topmargin="0" leftmargin="0" bottommargin="0" rightmargin="0">
<div style="height:10px; background:url(images/lead/lanmushodown.gif); width:960px;"><img src="images/spacer.gif" width="1" height="10" /></div>
</div>
<table width="960" border="0" cellspacing="0" cellpadding="0" align="center">
  <tr>
    <td rowspan="2">
   <div style="width:200px; height:366px; float:left">
    <div style="height:10px; background:url(images/lead/bgt.gif)"><img src="images/spacer.gif" width="1" height="10" /></div>
    <div style="height:366px; background:url(images/lead/bg.gif)" align="center"><div style="width: 160px"><table border="0" cellspacing="0" cellpadding="0" width='100%'>
<tr><td>
<div id="parent">
<ul id="navi">
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu1"  onclick="DoMenu('ChildMenu1')">电子数码<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu1" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=1">手机</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=2">照相机</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=3">MP3</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=4">MP4</a></li>
   <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=5">电脑配件</a></li>
    <li><a href="goodslist.asp?Cateid=8">收音机</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu2" onclick="DoMenu('ChildMenu2')">生活饰品<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu2" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=9">镜子</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=10">枕头</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=11">杯子</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=12">钟表</a></li>
    <li ><a href="goodslist.asp?Cateid=13">台灯</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px;"><a href="#Menu=ChildMenu3" onclick="DoMenu('ChildMenu3')">休闲娱乐<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu3" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=14">玩偶</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=15">盒子</a></li>
    <li><a href="goodslist.asp?Cateid=16">相框</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu4" onclick="DoMenu('ChildMenu4')">个人时尚<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu4" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=17">T恤</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=18">休闲包</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=19">鞋子</a></li>
    <li ><a href="goodslist.asp?Cateid=20">钱包</a></li>
    </ul>
</li>
<li style="border-bottom:1px solid #cccccc; padding-top:5px; padding-bottom:5px; "><a href="#Menu=ChildMenu5" onclick="DoMenu('ChildMenu5')">办公愉悦<span style="padding-left:30px;"><img alt="" src="images/lead/arrow.gif" border="0"/></span></a>
    <ul id="ChildMenu5" class="collapsed">
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=21">笔</a></li>
    <li style="border-bottom:1px solid #cccccc"><a href="goodslist.asp?Cateid=22">记事本</a></li>
    </ul>
</li>
</ul>
</div>
</td></tr></table>
</div>
    </div>
    <div style="height:35px; background:url(images/lead/bgb.gif)" align="right"><div style="padding-top:20px"></div>
    </div>
  </div>
    </td>
  </tr>
</table>
</body>
</html>

调试易

javascript+div+css写的树型下拉菜单不能正常显示（高分求救）

解决方案 »