(function (window, undefined) {
    var document = window.document,
    $ = function (id) {
        return $.fn.init(id);
    }
    $.fn = $.prototype = {
        init: function (id) {
            this.selector = document.getElementById(id) || id;
            return this;
        },
        alerttxt: function () {
            var selector = this.selector;
            return selector.innerHTML;
        },
        addid: function () {
            var txt = this.selector;
            alert(txt+"你好");
        }
    }

    $.fn.init.prototype = $.fn;
    window.$ = $;
})(window);