javascript面向对象之共享成员属性与方法及protot

<script language="javascript" type="text/javascript">
function Dog(){}
Dog.prototype.shout=function(){
 alert("hello,小狗");
}
Dog.prototype.name="黄色小狗";
var dog1 = new Dog();
var dog2 = new Dog();
dog1.shout();
dog2.shout();
dog1.name="小白";
window.alert(dog1.name+dog2.name);
</script>