Custom Event Handler

event.js

class Event {
  constructor() {
    this.events = {};
  }
  
  fire(event, data) {
    const Event = this.events[event];
    if( Event ) {
      Event.forEach(callback => {
        callback.call(null, data);
      });
    }
  }
  
  listen(event, callback) {
    if(!this.events[event]) {
      this.events[event] = [];
    }
    
    this.events[event].push(callback);
    return () => {
      this.events[event] = this.events[event].filter(eventCallback => callback !== eventCallback);
    }
  }
  
  list() {
  	return console.dir(this.events);
  }
 
}

let E = new Event();
E.listen('event:test-event', data => {
  console.log(data);
});

E.fire('event:test-event', {name: 'test'});

E.list();