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

Person.prototype.sayHello = function(){
    console.log(`Hello ${this.name}`)
}

function Employee(name,dept){
    // construcotr 的 prototype 的 constructor 會指會自己
    Employee._super.constructor.call(this,name)
    this.dept = dept
}

Employee.prototype.selfIntroduction = function(){
    //改成從 Property 中去讀
    Employee._super.sayHello.call(this)
    console.log(`In the ${this.dept} department`)
}

const subclass = (subC,superC) => {
    //處理prototype
    let subProto = Object.create(superC.prototype)
    //將原本 subC.prototype 的 Property 定義給 subProto (這裡和複製物件時用的方式相同)
    const arrOwnProperties = Object.getOwnPropertyNames(subC.prototype)
    arrOwnProperties.forEach( property => {
        const prototypeDesc = Object.getOwnPropertyDescriptor(subC.prototype,property)
        Object.defineProperty(subProto,property,prototypeDesc)
    })
    //將處理完後的 prototype 給 subC 的 protoype
    subC.prototype = subProto
    //定義 _super Property 為父類別的 prototype
    subC._super = superC.prototype
}

//設定 Person 和 Employee 為父子類別
subclass(Employee,Person)

const mary = new Employee('Mary','IT')

mary.selfIntroduction()
//會同時列出
/*
Hello Mary
In the IT department
*/