Q:

No Referer header in CORS request from IE or Firefox

I'm trying to send a CORS POST request to an server.
In Chrome, this works as expected - OPTIONS preflight request is sent to server, server responds with access control headers, POST request is sent. When I try to do this in IE or Firefox, no referer is sent with the OPTIONS request, so I cannot add the access-control-allow-origin header (as this is done programatically). 
Javascript is:
    $.ajax({
        url: $(this).attr('href'),
        type: 'POST',
        xhrFields: {
            withCredentials: true,
        },
        contentType: 'application/json; charset=utf-8;',
        data: JSON.stringify(data),
        success: function (response) {
            alert(response);
        },
    });
    return false;
});

The headers in Chrome are as follows: 

The headers in Firefox are as follows:

Is there a way to guarantee that the referrer will be sent with the OPTIONS preflight request? And if not - is there another way to get the referring URL so I can add the allow origin header?

A:

Solved this by using the Origin header that is sent along with the preflight request. So if the Origin URL is one of the acceptable hosts, add the access-control-allow-origin header with the originating url. 

