为什么节点属性都没输出呢
<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 a=document.getElementsByTagName("li");
for(var=i;i<a.length;i++){
document.write(a[i].nodeName+"<br>");
document.write(a[i].nodeValue+"<br>");
document.write(a[i].nodeType+"<br>");
}
</script>
</body>
</html>