向原型添加功能不起作用

Question

我试图像这样添加一个原型函数

function Dog(name, breed) {
    this.name = name;
    this.breed = breed;
}

function barkWithMe() {
    console.log("woof woof i am " + this.name);
}
Dog.prototype.bark = barkWithMe();

var snoopy = new Dog();
snoopy.bark();

但它显示错误

Uncaught TypeError: snoopy.bark is not a function

请告诉我我哪里错了.谢谢.

Answer 1

该行评估函数并将返回值设置undefined为Dog.prototype.bark:

Dog.prototype.bark = barkWithMe();

将其更改为:

Dog.prototype.bark = barkWithMe;