function Master(){

        //给动物喂食

        this.feed=function(animal,food){

            window.alert(animal.constructor);

            document.writeln("主人给"+animal.name+" 喂"+food.name);

        }

    }

    //写食物

    function Food(name){

        this.name=name;

        //...

    }

    function Fish(name){

        this.food=Food;

        this.food(name);

    }

    function Bone(name){

        this.food=Food;

        this.food(name);

    }

    function Peach(name){

        this.food=Food;

        this.food(name);

    }

        //动物

    function Animal(name){

        this.name=name;

        //...

    }

    function Cat(name){

        this.animal=Animal;//对象冒充

        this.animal(name);

    }

    function Dog(name){

        this.animal=Animal;

        this.animal(name);

    }

    function Monkey(name){

        this.animal=Animal;

        this.animal(name);

    }

    var cat=new Cat("小猫咪");

    var dog=new Dog("小狗");

    var fish=new Fish("小鱼");

    var bone=new Bone("骨头");

    var master=new Master();

    master.feed(cat,fish);

    master.feed(dog,bone);

    master.feed(new Monkey("小猴"), new Peach("水蜜桃"));