为什么显示未定义
为什么我这显示未定义
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>nextSibling</title>
</head>
<body>
<ul id="u1">
<li id="a">javascript</li>
<li id="b">jquery</li>
<li id="c">html</li>
</ul>
<ul id="u2">
<li id="d">css3</li>
<li id="e">php</li>
<li id="f">java</li>
</ul>
<script type="text/javascript">
function get_previousSlbling(m){
var a=m.previousSibling;
while(a!=null&&a.nodeType!=1){
a=a.previousSibling;
}
return a;
}
var a=document.getElementsByTagName("li")[1];
document.write(a.nodeName);
document.write("=");
document.write(a.innerHTMl);
var b=get_previousSibing(a);
if(b!=null){
document.write("<br/>previousSibling");
document.write(b.nodeName);
document.write("=");
document.write(b.innerHTML);
}else{
document.write("<br>"+b);
}
</script>
</body>
</html>
