eventManager.js

class EventManager {
  constructor () {
    this.events = {};
  }

  addListener (name, callback) {
    this.events[name] = callback;
  }

  removeListener (name) {
    delete this.events[name];
  }

  trigger (name, event) {
    if (this.events[name]) {
      this.events[name](event);
    }
  }
}

const em = new EventManager();

em.addListener('click', (event) => {
  console.log(event);
});

// console.log(em.events);
em.trigger('click', 'foofoofoo');
em.removeListener('click');
em.trigger('click', 'foofoofoo');