求大神帮忙看下这样写为什么不行啊= =
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
</head>
<body>
<ul id="con">
<li id="lesson1">javascript
<ul>
<li id="tcon"> 基础语法</li>
<li>流程控制语句</li>
<li>函数</li>
<li>事件</li>
<li>DOM</li>
</ul>
</li>
<li id="lesson2">das</li>
<li id="lesson3">dadf</li>
<li id="lesson4">HTML/CSS
<ul>
<li>文字</li>
<li>段落</li>
<li>表单</li>
<li>表格</li>
</ul>
</li></ul>
<script type="text/javascript">
var mylist = document.getElementById("tcon");
var x=mylist.parentNode.parentNode.parentNode.childNodes;
for(var i=0;i<x.length;i++)
{if(x[i].innerHTML=='HTML/CSS'){
document.write("HTML/CSS");}
else{
document.write(x[i].innerHTML);
}
}
</script>
</body>
</html>
