我从互联网上得到一个简单的AJAX演示代码，它动态地填充一个选择列表框与数据库中的值。它包含一个嵌入AJAX代码的html文件和一个PHP文件。
问题是这个代码在IE, Chrome, FireFox4中工作良好，但在FireFox3中不工作。请任何人解释一下并告诉我解决办法。代码如下供参考
城市表的数据库模式如下
id tinyint(4) primary key not null
city varchar(50)
countryid tinyint(4)
HTML文件
<html>
<head>
<script type="text/javascript">
function getCity(strURL)
{
alert("inside getCity function");
//var req = getXMLHTTP(); // function to get xmlhttp object
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
//xmlhttp=new XMLHttpRequest();
req=new XMLHttpRequest();
}
else
{// code for IE6, IE5
//xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
req=new ActiveXObject("Microsoft.XMLHTTP");
}
if (req)
{
req.onreadystatechange = function()
{
if (req.readyState == 4) { //data is retrieved from server
if (req.status == 200) { // which reprents ok status
document.getElementById('citydiv').innerHTML=req.responseText;
}
else
{
alert("There was a problem while using XMLHTTP:'n");
}
}
}
//alert(srtURL);
var sURL="findcity.php?country="+strURL;
req.open("GET", sURL, true); //open url using get method
req.send();
}
}
</script>
</head>
<body>
<form method="post" action="" name="form1">
Country : <select name="country" onChange="getCity(this.value)">
<option value="">Select Country</option>
<option value="1">india</option>
<option value="2">usa</option>
</select>
<br />City : <div id="citydiv">
<select name="select">
<option>Select City</option>
</select>
</div>
</form>
</body>
</html>
<?
echo $_GET['country'];
echo "<br>";
$country=intval($_GET['country']);
echo $country;
echo "<br>";
$link = mysql_connect('localhost', 'root', 'mark'); //change the configuration if required
if (!$link) {
die('Could not connect: ' . mysql_error());
}
mysql_select_db('querytest'); //change this if required
$query="select city from city where countryid=$country";
echo "<br>";
echo $query;
echo "<br>";
$result=mysql_query($query);?>
<select name="city">
<option>Select City</option>
<? while($row=mysql_fetch_array($result)) { ?>
<option value><?=$row['city']?></option>
<? } ?>
</select>
请指导我的朋友使这段代码在FireFox 3中工作
变化
req.send();
req.send(null);