Method off

src/tutorial/tutorialManager.js:149–157

* Unregister event listener * @param {string} event - Event name * @param {Function} callback - Callback function

(event, callback)

   * @param {Function} callback - Callback function
   */
  off(event, callback) {
    if (this.listeners.has(event)) {
      const callbacks = this.listeners.get(event);
      const index = callbacks.indexOf(callback);
      if (index > -1) {
        callbacks.splice(index, 1);
      }
    }
  }

  /**
   * Emit event