var Class = function (parent) {    var klass = function () {        this.init.apply(this, arguments);    }    if (parent) {        /**         *  所有的子类都共享了同一个原型         *  避免在继承类的时候创建实例,只有实例的属性才会被继承         *  而非类的属性,设置对象的__proto__         * **/        var ctor = function () {        };        ctor.prototype = parent.prototype;        klass.prototype = new ctor;    }    klass.prototype.init = function () {    }    //prototype别名    klass.fn = klass.prototype;    //定义类的别名    klass.fn.parent = klass;    klass.__super__ = klass.__proto__;    //给类添加属性    klass.extend = function (obj) {        var extended = obj.extended;        for (var i in obj) {            klass[i] = obj[i];        }        if (extended) extended(klass);    }    //给实列添加属性    klass.include = function (obj) {        var included = obj.included;        for (var i in  obj) {            klass.fn[i] = obj[i];        }        //触发回调        if (included) included(klass);    }    return klass;}var Animal = new Class;Animal.include({    breath:function () {        console.log("breath")    }})var Cat = new Class(Animal)var tommy = new Cat;console.log(tommy)