A super-basic Javascript (publish subscribe) pattern

events.js

/**
 * A super-basic Javascript (publish subscribe) pattern
 * https://www.youtube.com/watch?v=nQRXi1SVOow
 * https://gist.github.com/learncodeacademy/777349747d8382bfb722
 *
 * @export
 * @class Events
 */
export default class Events {

  /**
   * Creates an instance of Events.
   *
   * @memberOf Events
   */
  constructor() {

    if (!Events.instance) {
      Events.instance = this;
    }

    this.events = {};

    return Events.instance;
  }

  /**
   * Events bindings
   *
   * @param {string} eventName - event Name
   * @param {Function} fn -
   *
   * @memberOf Events
   */
  on(eventName, fn) {
    this.events[eventName] = this.events[eventName] || [];
    this.events[eventName].push(fn);
  }

  /**
   * Unbind event
   *
   * @param {string} eventName - event Name
   * @param {Function} fn -
   *
   * @memberOf Events
   */
  off(eventName, fn) {
    const {events} = this;

    if (events[eventName]) {

      for (let i = 0; i < events[eventName].length; i++) {

        if (events[eventName][i] === fn) {

          this.events[eventName].splice(i, 1);

          break;
        }
      }
    }
  }

  /**
   * Trigger a specific event
   *
   * @param {string} eventName - event Name
   * @param {...*} [params] -
   *
   * @memberOf Events
   */
  trigger(eventName, ...params) {

    const {events} = this;

    if (events[eventName]) {
      events[eventName].forEach((fn) => {
        fn(...params);
      });
    }
  }
}