クラスの複製デザパタです

ICloneable.js

class Human{
    constructor(name, age){
        this.name = name;
        this.age = age;
    }
    static clone(obj){ return new this(obj.name, obj.age); }
}

class Woman extends Human{}

class Gao extends Human{
    constructor(fav){
        super("gao", 18);
        this.fav = fav;
    }
    static clone(obj){ return new this(obj.fav); }
}

var foo = new Human("foo", 20);
console.log(foo);              // Human { name: "foo", age: 20 }
console.log(Woman.clone(foo)); // Woman { name: "foo", age: 20 }

var gao  = new Gao("sushi");
var gao2 = Gao.clone(gao);
gao2.fav = "beaf";

console.log(gao);  // Gao { name: "gao", age: 18, fav: "sushi" }
console.log(gao2); // Gao { name: "gao", age: 18, fav: "beaf" }