//父类

function BaseFun() {

    var hello = "HelloWorld";

    this.HelloPublic = "Hello--World";

    var privatefun = function () {

        alert("hellow");

    }

    this.publicfun = function () {

        var a = this.HelloPublic;

        alert("this is public funtion" + a);

    }

}

//子类

function  SubFun() {

    BaseFun.apply(this, arguments);// 建立继承关系

    this.SubHello = function () {

        alert("sub ok");

    }

}

//动物基类

function  BaseAnimal() {

    this.Type = "Animal";

    this.Eat = function () {

        alert(this.Type + "会吃东西方法");

    }

    this.Walter = function () {

        alert(this.Type + "喝水");

    }

}

//猪子类

function  Pie() {

    //子类方法覆盖父类方法

    this.Eat = function (arg) {

        alert(arg);

    }

}

//狗子类

function Dog() {

}

//prototype属性，指定为该属性的值，该构造器的实例对象自动继承

Dog.prototype={

    eatfood:function () {

        alert("吃东西");

    },

    sleep:function () {

        alert("睡觉");

    }

};

     function  getFun() {

            var basef=new BaseFun();

            var a=basef.HelloPublic;

            basef.HelloPublic="我是父类";

            basef.publicfun();

            var sub=new SubFun();

            sub.HelloPublic="我是子类";

            sub.publicfun();

            var pie=new Pie();

            pie.Eat("吃东西");

            //建立继承关系

            Pie.prototype=new BaseAnimal();

            var p=new Pie();

            p.Type="猪";

            p.Walter();

            var dog=new Dog();

            dog.sleep();

            dog.eatfood();

        }