(function (window, undefined) {

    //将 document 封装成 jQuery 对象并缓存

    var rootjQuery,

    //dom ready 事件的委托队列

        readyList,

    //快速地识别 html 标记 如 <div> 或者 #id

        rquickExpr = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]*))$/,

        jQuery = function (selector, context) {

            return new jQuery.fn.init(selector, context, rootjQuery);

        };

    jQuery.fn = jQuery.prototype = {

        constructor: jQuery,

        init: function (selector, context, rootjQuery) {

            // $(""), $(null), $(undefined), $(false)

            if (!selector) {

                return this;

            }

            var match = rquickExpr.exec(selector);

            // $('<div></div>')

            jQuery.parseHTML(match[1])

            return this;

            // $(#id)

            return document.getElementById(selector);

            // $('.class'),  $('.class', context),  $('#class', context)

            // 其中 context 是jQuery元素

            return (context || rootjQuery).find(selector);

            // $('.class', domElm)

            return this.constructor(context).find(selector);

            // selector is function

            return rootjQuery.ready(selector);

            return jQuery.makeArray(selector, this);

        },

        ready: function (fn) {

            // Add the callback

            jQuery.ready.promise().done(fn);

            return this;

        }

    }

    jQuery.init.prototype = jQuery.fn;

    jQuery.extend = jQuery.fn.extend = function () {

    };

    rootjQuery = jQuery(document);

    // Sizzle 代码

    (function (window, undefined) {

        function Sizzle(selector, context, results, seed) {

            if (support.qsa) {

                return querySelectorAll(selector)

            }

            return select(selector.replace(rtrim, "$1"), context, results, seed);

        }

        function select(selector, context, results, seed) {

            var match = tokenize(selector);

        }

        function tokenize(selector, parseOnly) {

        }

        jQuery.find = Sizzle;

    })(window);

    // 对 jQuery 对象的扩展

    jQuery.extend({});

    // 对 jQuery.fn 对象的扩展

    jQuery.fn.extend({});

    window.$ = window.jQuery = jquery;

})(window);