I would like to add a custom header to an AJAX POST request from jQuery.

I have tried this:

$.ajax({
    type: 'POST',
    url: url,
    headers: {
        "My-First-Header":"first value",
        "My-Second-Header":"second value"
    }
    //OR
    //beforeSend: function(xhr) { 
    //  xhr.setRequestHeader("My-First-Header", "first value"); 
    //  xhr.setRequestHeader("My-Second-Header", "second value"); 
    //}
}).done(function(data) { 
    alert(data);
});

When I send this request and I watch with FireBug, I see this header:

  
OPTIONS xxxx/yyyy HTTP/1.1

      Host: 127.0.0.1:6666

      User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:11.0) Gecko/20100101 Firefox/11.0

      Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8

      Accept-Language: fr,fr-fr;q=0.8,en-us;q=0.5,en;q=0.3

      Accept-Encoding: gzip, deflate

      Connection: keep-alive

      Origin: null

      Access-Control-Request-Method: POST
Access-Control-Request-Headers: my-first-header,my-second-header

      Pragma: no-cache

      Cache-Control: no-cache

Why do my custom headers go to Access-Control-Request-Headers:

  
Access-Control-Request-Headers: my-first-header,my-second-header

I was expecting a header values like this:

  
My-First-Header: first value

     My-Second-Header: second value

Is it possible?