Ajax调用子域到域

I have some troubles with ajax cross-scripting request using jquery. I'm in a subdomain named test.example.com and i'm doing a ajax call to www.example.com/action like this :

$.ajax({ 
url:"http://www.example.com/action",
type:"post", 
crossDomain:true,
dataType:"jsonp",
jsonp:"cross_domain_action",
xhrFields:{withCredentials:true},
success:function(data){}
});

The problem is that i dont know how to test if the request is an ajax one or not in www.example.com/action.

I'm using CakePHP 1.3 and there is a component call "request_handler.php" with the function

function isAjax() {
    return env('HTTP_X_REQUESTED_WITH') === "XMLHttpRequest";
}

I found that there is not that HTTP header in the request.

X-Requested-With    XMLHttpRequest

If you have any ideas :) Thanks

Well that's exactly what you use to test if it's and ajax request. I usually use:

if(isset($_SERVER['HTTP_X_REQUESTED_WITH']) 
&& strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') 
{//this is an ajax request}

You don't need to manually check the headers. Cake 1.3 provides this information in the controller's $this->params property:

$this->params['isAjax']

will store 1 if the current request is an ajax call and 0 if not. Check it here. .