I'm trying to send a cross-origin domain and adding a custom 'Authorization'-header. Please see the code below.
Error:
XMLHttpRequest cannot load {url}. Request header field Authorization is not allowed by Access-Control-Allow-Headers.
function loadJson(from, to) {
    $.ajax({
        //this is a 'cross-origin' domain
        url : "http://localhost:2180/api/index.php",
        dataType : 'json',
        data : { handler : "statistic", from : from, to : to
        },
        beforeSend : setHeader,
        success : function(data) {
            alert("success");
        },
        error : function(jqXHR, textStatus, errorThrown) {
            alert("error");
        }
    });
}
function getToken() {
    var cookie = Cookie.getCookie(cookieName);
    var auth = jQuery.parseJSON(cookie);
    var token = "Token " + auth.id + ":" + auth.key;
}
function setHeader(xhr) {
    xhr.setRequestHeader('Authorization', getToken());
}
I also tried:
headers : { 'Authorization' : getToken() },
in the ajax request.
Could it be that the jquery-ajax framework is blocking cross-origin Authentification? How can I fix this?
Update:
By the way: is there a safer method to store the auth.key on client-side then in a cookie? getToken() will be replaced with a more complex method, hashing the body, date,etc.
 
     
    