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发表于 2007-9-18 21:17

node[i] has no properties是怎么回事?

我做一个例子,根据输入的省,显示地市,但是在执行过程中,firefox报了一个node has no properties的错误,不知其原因,望大侠赐教!代码如下:
<script type='text/javascript'>
var req;
function usernamecheck(){
var user_name = document.getElementById("username".value; /* 取得变量值*/
var url = "/ajaxmi/pre?username="+user_name; /*组装URL*/
if(window.XMLHttpRequest){ /*判断XMLHttpRequest*/
req = new XMLHttpRequest; /*建立变量*/
}else if(window.ActiveXObject){
req = new ActiveXObject("Microsoft.XMLHTTP";
}
if(req){
req.open("GET",url,true); /*发送URL*/
req.onreadystatechange = callback; /*请求返回时执行的方法*/
req.send(null);
}
}

function callback(){
if(req.readyState == 4){ /*判断返回是否成功*/
if(req.status == 200){
showmessage(); /*业务逻辑方法*/
}else{
alert(req.statusText);
}
}else{
document.getElementById("showinfo".innerHTML="SHOWING......";
}
}

function showmessage(){
      var xmlDoc = req.responseXML.documentElement;
      var node = xmlDoc.getElementsByTagName('info');
      var str="<select id='city_no'>";
for (i=0;i<=node.length;i++){
str=str+"<option>"+node.firstChild.nodeValue+"</option>"; 
}
str+="</select>";
document.getElementById("cityno".innerHTML=str;
}

</script>
<html>
<form name="showform" >
user_name:<input type="text" id="username" onBlur="usernamecheck()"><br>
<span id='showinfo'></span>
<select id='cityno'>
        <option selected>请选择</option>
</select>

</form>
</html>