进阶的继承

var Person = function(name){
    this.name = name || "noName";
}
Person.prototype.getName = function(){
    return `我的名字是： ${this.name}`;
} 

var Student = function(name){
    this.grade = 1;
    this.name = name
}
Student.prototype = new Person();
Student.prototype.getGrade = function(){
    return this.grade;
}

var lixiao = new Student("lixiao");

console.log(lixiao.name);    //lixiao
console.log(lixiao.getName());    //我的名字是： 李骁  
console.log(lixiao.getGrade());    //1
console.log(lixiao instanceof Student);   //true
console.log(lixiao instanceof Person);    //true
console.log(lixiao.__proto__ === Student.prototype);   //true
console.log(lixiao.__proto__.__proto__ === Person.prototype);   //true