Javascript 原型(prototype)继承怪异

Question

我正在尝试处理一些 javascript 继承示例，但我遇到了这个问题:

function Animal(){}
Animal.prototype.type = "animal";
Animal.prototype.speak = function(){ console.log( "I'm a " + this.type + 
    ". I can't really talk ;)" ); }

function Dog(){}

function F(){}
F.prototype = Animal.prototype;

Dog.prototype = new F();
Dog.prototype.constructor = Dog;
Dog.prototype.type = "Dog";
Dog._super = Animal.prototype;
Dog.woof = function(){ console.log( "Woof!" ); _super.speak(); }

var rover = new Dog();
rover.woof();

我得到了这个，但我不知道为什么:

TypeError: Object #<Dog> has no method 'woof'

我知道我可以将未找到的方法放入构造函数中，但我试图通过修改原型(prototype)来做到这一点。我在这里做错了什么？

Answer 1

改变:

Dog._super = Animal.prototype;
Dog.woof = function(){ console.log( "Woof!" ); _super.speak(); }

收件人:

// Dog.prototype._super = Animal.prototype; <- you can remove this line
Dog.prototype.woof = function(){ console.log( "Woof!" ); this.speak(); }