SOURCE

/*定义一个人类*/  
function Person(name,age)  {  
    this.name=name;  
    this.age=age;  
}  
/*定义一个学生类*/  
function Student(name,age,grade)  {  
    Person.apply(this,arguments);  
    this.grade=grade;  
}  
//创建一个学生类  
var student=new Student("zhangsan",21,"一年级");  
//测试  
console.log("name:"+student.name+"\n"+"age:"+student.age+"\n"+"grade:"+student.grade);