function Ajax() {}
var ajax = new Ajax();

(function () {
    'using strict';
    var proto = Ajax.prototype;

    proto.getRequest = function (method, url, cb) {
        var r = new XMLHttpRequest;
        r.open(method, url);
        r.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
        r.onload = function () {
            typeof cb == 'function' && cb(r.response, r.status, r);
        };
        return r;
    };

    proto.get = function (url, cb) {
        this.getRequest('GET', url, cb).send();
    };

    proto.update = function (url, elem) {
        this.get(url, function (data) {
            val(elem, data);
        });
    };

    proto.post = function (url, params, cb) {
        var r = this.getRequest('POST', url, cb), data = '', p;
        r.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        for (p in params) {
            if (params.hasOwnProperty(p)) {
                if (data.length) data += '&';
                data += p + '=' + encodeURIComponent(params[p]);
            }
        }
        r.send(data);
    };

    proto.submit = function (frmElem, targetElem) {
        frmElem = ge(frmElem);
        var data = new FormData(frmElem);
        this.getRequest('POST', frmElem.action, function (data) {
            val(targetElem, data);
        }).send(data);
    };
})();


// ...
function ge(el) {
    return isElement(el) ? el : document.getElementById(el);
}

function val(el, v) {
    el = ge(el);
    var i = /^(INPUT|TEXTAREA)$/.test(el.tagName) ? 'value': 'innerHTML';
    return arguments.length > 1 ? el[i] = v : el[i];
}

function extend(Child, Parent) {
    var F = function () {};
    F.prototype = Parent.prototype;
    Child.prototype = new F();
    Child.prototype.constructor = Child;
}

function clone(o) {
    if (o == null || typeof o != 'object')
        return o;
    var copy = o.constructor();
    for (var p in o)
        copy[p] = clone(o[p]);
    return copy;
}

function isElement(o) {
    return o instanceof HTMLElement;
}