Question

js 继承为什么运行的时候总是弹出undefined

关于js的继承，求大侠指点，为什么总是unfined。代码如下

function Animal(){};

Animal.prototype.species = "动物";

function dog(name,color){
/ar F = function(){};

/*　　F.prototype = Animal.prototype; */

this.name=name;
this.color=color;

dog.prototype =new Animal()

　dog.prototype.constructor= dog;

// dog.prototype=new Animal();
// dog.prototype.constructor=dog();

};

var dog1=new dog("大狗","黑色");
alert(dog1.species);