继承之es5对比es6

function Person(name){
    this.name = name;
}

Person.prototype.sayName = function() {
    alert(this.name);
}  

function VipPerson(name,level){
　　Person.call(this,name);
　　this.level = level;
}　　
// 组合继承(缺点是prototype这一层多了一些无用的undefined属性)
// VipPerson.prototype = new Person();
// VipPerson.prototype.constructor = VipPerson; //重写construtor

// 寄生组合继承
VipPerson.prototype = Object.create(Person.prototype, {
    constructor: { //重写construtor
        value: VipPerson,
        enumerable: false,
        configurable: true,
        writable: true
    }
})

var vipPerson = new VipPerson('amie',3);

class Person{
    constructor(name){
        this.name = name; 
    }
    sayName(){
       alert(this.name);      
    }
}

class VipPerson extends Person{
    constructor(name,level){
        super(name);
        this.level = level;
    }
}    

var person2 = new VipPerson('rick',3)