var doc = document.implementation.createDocument("club", null);

var xhttp = new XMLHttpRequest();

xhttp.onreadystatechange = function () {
    if (xhttp.readyState == 4 && xhttp.status == 200) {

        var xmlDoc = xhttp.responseXML; //important to use responseXML here
    }
    xhttp.open("GET", "club.xml", true);
    xhttp.send();
}

var clubElem = doc.createElement("club");
var clubNameElem = doc.createElement("name");
var nameNode = doc.createTextNode("Barcelona FC");
clubNameElem.appendChild(nameNode);
clubElem.appendChild(clubNameElem);

var ownerElem = doc.createElement("owner");
var ownerName = doc.createElement("name");
var ownerNameNode = doc.createTextNode("Bertomeo");
var ownerNationalityNode = doc.createTextNode("Spanish");
ownerElem.appendChild(ownerNameNode);
ownerElem.appendChild(ownerNationalityNode);
clubElem.appendChild(ownerElem);

var valueElem = doc.createElement("value");
var valueNode = doc.createTextNode("4.23 b $");
valueElem.appendChild(valueNode);
clubElem.appendChild(valueElem);

var stadiumElem = doc.createElement("stadium");
var stadiumName = doc.createElement("name");
var stadiumNameNode = doc.createTextNode("Camp Nou");
stadiumNameElem.appendChild(stadiumNameNode);
var capacityElem = doc.createElement("capacity");
var capacityNode = doc.createTextNode("90 000");
capacityElem.appendChild(capacityNode);
var ticketPriceElem = doc.createElement("ticketPrice");
var ticketPriceNode = doc.createTextNode("100 $");
ticketPriceElem.appendChild(ticketPriceNode);
stadiumElem.appendChild(stadiumNameElem);
stadiumElem.appendChild(capacityElem);
stadiumElem.appendChild(ticketPriceElem);
clubElem.appendChild(stadiumElem);

var foundedElem = doc.createElement("founded");
var foundedNode = doc.createTextNode("1898");
foundedElem.appendChild(foundedNode);
clubElem.appendChild(foundedElem);

var trophiesElem = doc.createElement("trophies");
var trophiesNode = doc.createTextNode("64");
trophiesElem.appendChild(trophiesNode);
clubElem.appendChild(trophiesElem);

var squadElem = doc.createElement("squad");
var footballPlayerElem = doc.createElement("footballPlayer");
var playerNameElem = doc.createElement("name");
var playerNameNode = doc.createTextNode("Messi");
playerNameElem.appendChild(playerNameNode)
playerSalaryElem.appendChild(playerSalaryNode);
var playerSalaryElem = doc.createElement("salary");
var playerSalaryNode = doc.createTextNode("500 000 $");
playerNameElem.setAttribute("position","нападател");
playerNameElem.setAttribute("shirtNo","10");
footballPlayerElem.appendChild(playerNameNode);
footballPlayerElem.appendChild(playerSalaryNode);
squadElem.appendChild(footballPlayerElem);
club.appendChild(squadElem);