为什么给li加id不行
<body>
<ul id="test"><li>JavaScript</li><li id="ht">HTML</li></ul>
<script type="text/javascript">
var otest = document.getElementById("test");
var node=document.getElementById("ht");
var newnode=document.createElement("li");
newnode.innerHTML="php";
node.insertBefore(newnode,node);
</script>
</body>
