1. We can add methods to each instance object. In other words, we need to create it every time we use a method outside the 'class'.
function Dog(){
window.alert('I am a dog!');
}
var dog1=new Dog();//实例化一个对象
//现在由于类Dog功能单一，无法满足对象dog1的需要，现在就要考虑为对象dog1新增加一个方法
function eat(){
window.alert('I like eat bone!');
}
dog1.Dog_eat=eat;
dog1.Dog_eat();//此时就可以调用方法eat了，不过使用的是一个指针Dog_eat指向eat();所以也只能该对象使用
2. What if you want every object created through the Dog class to use the method eat() without having to go through tedious introduction?
function Dog(){
window.alert('I am a dog!');
}
Dog.prototype.Dog_eat=function(){
window.alert('I like eat bone')
}
var dog1=new Dog();
dog1.Dog_eat;
var dog2=new Dog();
dog2.Dog_eat;
From now on, every object can use the Dog_eat() method.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
