求教代码哪里错了
<script type="text/javascript">
var x=document.getElementsById("con");
for(var i in x.childNodes){
if(x.childNodes[i].nodeType!=1){
x.removeChild(x.childNodes[i]);
}
}
document.write(x.firstChild.nodeName+","+x.firstChild.nodeValue);
document.write(x.lastChid.nodeName+","+x.lastChild.nodeVale);
</script>