fun

function HeaderIdentification(header,value){

    var myHeader = XMLHttpRequest.setRequestHeader(header, value);
    // get all HTTP headers
    var req = new XMLHttpRequest();
    req.open('Get',document.location,false);
    req.send(null);
    var headers = req.getAllResponseHeaders().toLowerCase();
    for(var i = 0; i < headers.length;i++){
        if(headers[i] == myHeader){
            console.log("Found");
        }
    }

}

HeaderIdentification("Mirela",1200);