为什么没有输出？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>节点属性</title>
</head>
<body>
<ul>
<li>javascript</li>
<li>HTML/CSS</li>
<li>jQuery</li>
</ul>
<script type="text/javascript">
var lists = document.getElementsByTagName("li");
document.write(list.length);
for(var i=0;i<lists.length;i++)
{
document.write("第"+(i+1)+"个节点的名称是："+lists[i].nodeName+<br />);
document.write("第"+(i+1)+"个节点的值是："+lists[i].nodeValue+<br />);
document.write("第"+(i+1)+"个节点的类型是："+lists[i].nodeType+<br />);
}
</script>
</body>
</html>
