jQuery Ajax实现跨域请求

<script type="text/javascript" src="http://www.youxiaju.com/js/jquery-1.4.2.min.js"></script> 
<script type="text/javascript"> 
$(function(){ 
$.ajax( 
  { 
    type:'get', 
    url : 'http://www.youxiaju.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).")";