EnterpriseServiceBus in ES6

EnterpriseServiceBus.babel.js

class Bus {
    constructor() {
        this.handlers = {};
    }
    
    subscribe(type, handler) {
        this.handlers[type] = (this.handlers[type] || [])
            .concat(handler);
    }

    unsubcribe(type, handler) {
        this.handlers[type] = (this.handlers[type] || [])
            .filter(h => handler !== h);
    }

    publish(type, message) {
        const handlers = this.handlers[type];

        if (handlers) {
            handlers.forEach(handler => handler(message));
        }

        const base = Object.getPrototypeOf(type);

        return base && (this.publish(base, message) || !!handlers);
    }
}

class Message {}
class Written extends Message {}
class Really extends Written {}

const writtenHandler = m => console.log(m.name);

const bus = new Bus();
bus.subscribe(Written, writtenHandler);
bus.subscribe(Really, m => console.log("rly"));
bus.subscribe(Message, m => console.log("lolz!"));

bus.publish(Really, {name: 'derp'});

bus.unsubcribe(Written, writtenHandler);

bus.publish(Really, {name: 'derp'});