Implementation method of dynamically adding classes in Javascript

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.