Method on

src/js/youtube_player.js:106–115

(event, callback)

  }

  on(event, callback) {
    if (
      typeof this.listeners[event] == "undefined" ||
      this.listeners[event] == null
    ) {
      this.listeners[event] = [];
    }

    this.listeners[event].push(callback);
  }

  off(event, callback) {
    if (