jquery ajax 跨域请求代码

<script type="text/javascript" src="/js/jquery-1.4.2.min.js"></script> 
<script type="text/javascript"> 
$(function(){ 
$.ajax( 
{ 
type:'get', 
url : 'http://www.jb200.com/validate.php?loginuser=lee&loginpass=123456', 
dataType : 'jsonp', 
jsonp:"jsoncallback", 
success  : function(data) { 
alert("用户名："+ data.user +" 密码："+ data.pass); 
}, 
error : function() { 
alert('fail'); 
} 
} 
); 
}) 
</script> 

<?php 
header('Content-Type:text/html;Charset=utf-8'); 
$arr = array( 
"user" => $_GET['loginuser'], 
"pass" => $_GET['loginpass'], 
"name" => 'response' 
 
); 
echo $_GET['jsoncallback'] . "(".json_encode($arr).")";