向原型添加功能不起作用

Question

I am trying to add a function to prototype like this

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();

But it displays an error

Uncaught TypeError: snoopy.bark is not a function

Please tell me where am I wrong. Thanks.

Answer 1

This line evaluates the function and sets the return value undefined to Dog.prototype.bark :

Dog.prototype.bark = barkWithMe();

Change it to:

Dog.prototype.bark = barkWithMe;