gistfile1.js

build = function(tag, attrs){
    var node = document.createElement(tag);
    for(var k in attrs) {
        node.setAttribute(k, attrs[k])
    }
    return node;
};

text = function(text) {
    return document.createTextNode(text);
};

xml = function(tag, attrs, closure){
    var node = build(tag, attrs);

    if(closure) {
        var scope = {
                  xml: function(tag, attrs, closure) { node.appendChild(xml(tag, attrs, closure));},
                  text: function(t) { node.appendChild(text(t)); }
                 };

        closure.apply(scope);
    }

    return node;
};

/*
var iq = xml('iq', {xmlns: "http:..."}, function() {
    this.xml('query', {xmlns: 'http://jabber.org/protocol/disco#items', node: "root"}, function() {
        for(var i = 0; i < 10; i++){
            this.xml('item', {}, function() {
                this.text('item-' + i);
            });
        }
    });
});

output

<iq xmlns="http:...">
  <query xmlns="http://jabber.org/protocol/disco#items" node="root">
    <item>item+1</item>
    <item>item+2</item>

    <item>item+9</item>
  </query>
</iq>
*/