Question

我有一个简单的原型链，我想得到所有原型的名称：

function Animal(name, age){
    this.name = name;
    this.age = age;

    this.eat = function(){console.log(name + " eats");}
    this.getAge = function(){console.log(name + " is " + age + " years old");}
}

function Cat(name, age){
    Animal.call(this, name, age);
    this.hunt = function(){console.log(name + " hunts mice")};
}
Cat.prototype = new Animal();

var cat1 = new Cat("cat1", 2);

var currentPrototype = cat1;
while(currentPrototype != null){
    console.log(currentPrototype.constructor.name);
    currentPrototype = Object.getPrototypeOf(currentPrototype);
}

我希望得到Cat，然后是Animal，然后是Object。但是，我得到了：

Animal
Animal
Animal
Object

有人可以向我解释为什么会发生这种情况，以及如何获得正确的结果。我的整个原型继承是错误的吗？

Answer 1

当你Cat.prototype = new Animal();时，你做了

儿童的

[[prototype]]是Parent的参考。

这会更改指向父级的子构造函数。

您需要明确设置

Cat.prototype.constructor = Cat;

见下面的例子：

＆＃13;

function Animal(name, age){
    this.name = name;
    this.age = age;

    this.eat = function(){console.log(name + " eats");}
    this.getAge = function(){console.log(name + " is " + age + " years old");}
}

function Cat(name, age){
    Animal.call(this, name, age);
    this.hunt = function(){console.log(name + " hunts mice")};
}
Cat.prototype = new Animal();

Cat.prototype.constructor = Cat;
var cat1 = new Cat("cat1", 2);

var currentPrototype = cat1;
while(currentPrototype != null){
    console.log(currentPrototype.constructor.name);
    currentPrototype = Object.getPrototypeOf(currentPrototype);
}

＆＃13;

获取原型链

1 个答案: