为什么我的otest换成node就没用？？我在id上加了node了啊
<!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="test"><li>JavaScript</li><li id= "node">HTML</li></ul>
<script type="text/javascript">
var otest = document.getElementById("test");
var node=document.getElementById("node");
var newnode=document.createElement("li");
newnode.innerHTML="PHP";
otest.insertBefore(newnode,node);
</script>
</body>
</html>
