Prototype.js

'use strict';

class Prototype {
    constructor(prototype) {
        console.log("Prototype Class created");
    }

    setFeature(key, val) {
        this[key] = val
    }

    clone() {
        console.log("Prototype.clone invoked");
    }
}

class ConcretePrototype1 extends Prototype {
    constructor() {
        super();
        console.log("ConcretePrototype1 created");
        this.feature = "feature 1"
    }

    clone() {
        console.log('ConcretePrototype1.clone invoked');
        let clone = new ConcretePrototype1();
        let keys = Object.keys(this);

        keys.forEach(k => clone.setFeature(k, this[k]));

        console.log("ConcretePrototype1 cloned");
        return clone;
    }
}

class ConcretePrototype2 extends Prototype {
    constructor() {
        super();
        console.log("ConcretePrototype2 created");
        this.feature = "feature 2"
    }

    clone() {
        console.log('ConcretePrototype2.Clone function');
        let clone = new ConcretePrototype2();
        let keys = Object.keys(this);

        keys.forEach(k => clone.setFeature(k, this[k]));
        console.log("ConcretePrototype2 cloned");
        return clone;
    }
}

var proto1 = new ConcretePrototype1();
proto1.setFeature('feature', "feature 11");
var clone1 = proto1.clone();
console.log(clone1.feature);
console.log(typeof clone1);
console.log(clone1 === proto1);

var proto2 = new ConcretePrototype2();
proto2.setFeature('feature', "feature 22");
var clone2 = proto2.clone();
console.log(clone2.feature);
console.log(typeof clone2);
console.log(clone2 === proto2);