原型式继承解决问题

 function Animal(gender,age){
      this.gender = gender;
      this.age = age;
    }
    Animal.prototype.eat = function(){
      console.log(‘会吃东西‘);
    }
    function Dog(gender,age,color){
      this.gender = gender;
      this.age = age;
      this.color = color;
    }
    //原型替换，将狗的原型替换成动物的实例
    Dog.prototype = new Animal();
    Dog.prototype.lookHouse = function() {
      console.log(‘会看家‘);
    }
    var dog = new Dog(‘公‘,‘2‘,‘color‘);
    console.log(dog);
    dog.eat();
    dog.lookHouse();