Facebook App/Page Tab with xmlHttpRequest doesn't work in Firefox - ajax

Question

I have e really big problem with firefox and facebook.
I mad an application on my webserver which uses xmlHttpRequest. I added this application to a facebook tab on a test facebook page. It works with IE, Chrome, Safari but not with firefox.
The request just keeps loading until timeout.
The JS functions i'm using:
function createXmlHttpRequest() {
try {
if (typeof ActiveXObject != 'undefined') {
return new ActiveXObject('Microsoft.XMLHTTP');
} else if (window["XMLHttpRequest"]) {
return new XMLHttpRequest();
}
} catch (e) {
changeStatus(e);
}
return null;
};
function downloadUrl(url, callback) {
var status = -1;
var request = createXmlHttpRequest();
if (!request) {
return false;
}
request.onreadystatechange = function() {
if (request.readyState == 4) {
try {
status = request.status;
} catch (e) {
}
if (status == 200) {
callback(request.responseXML, request.status);
request.onreadystatechange = function() {};
}
}
}
request.open('GET', url, f);
try {
request.send(null);
} catch (e) {
changeStatus(e);
}
};
function xmlParse(str) {
if (typeof ActiveXObject != 'undefined' && typeof GetObject != 'undefined') {
var doc = new ActiveXObject('Microsoft.XMLDOM');
doc.loadXML(str);
return doc;
}
if (typeof DOMParser != 'undefined') {
return (new DOMParser()).parseFromString(str, 'text/xml');
}
return createElement('div', null);
}
function downloadScript(url) {
var script = document.createElement('script');
script.src = url;
document.body.appendChild(script);
}
i call it through downloadUrl()
The Headers from the requested files:
header('Access-Control: allow <*>');
header("Access-Control-Allow-Origin: *");
header('Access-Control-Allow-Methods: GET');
header('Access-Control-Allow-Headers: X-PINGOTHER');
header("Content-type: text/xml");
i really tried everything, but it won't work in firefox...
what i've noticed: by observing firebug while loading this app in the facebook tab i could see that facebook is not requesting the adress given in the source, but other ones like: https://0-317.channel.facebook.com/pull?channel=p_1495135952&seq=389&partition=7&clientid=420773d2&cb=682&idle=0&state=active
i think it's surely firefox cross domain policy... but how can i solve this problem?
Anyone had the same problems ?
I thank you in advance.
Greetings

Answer 1

ok, found the problem.
Facebook is using UTF-8, but my page wasn't. So the stopped at the umlauts.
So it wasn't the Request at all.