Yahoo! UI Library

Y.Node.prototype._ioComplete = function(code, response, args) {
    var selector = args[0],
        callback = args[1],
        tmp,
        content;

    if (response && response.responseText) {
        content = response.responseText;
        if (selector) {
            tmp = Y.DOM.create(content);
            content = Y.Selector.query(selector, tmp);
        }
        this.setContent(content);
    }
    if (callback) {
        callback.call(this, code, response);
    }
};

Y.Node.prototype.load = function(url, selector, callback) {
    if (typeof selector == 'function') {
        callback = selector;
        selector = null;
    }
    var config = {
        context: this,
        on: {
            complete: this._ioComplete
        },
        arguments: [selector, callback]
    };

    Y.io(url, config);
    return this;
}