constructor() {
    /**
     * @type {{ [T in keyof PhotoSwipeEventsMap]?: ((event: AugmentedEvent<T>) => void)[] }}
     */
    this._listeners = {};
    /**
     * @type {{ [T in keyof PhotoSwipeFiltersMap]?: Filter<T>[] }}
     */

    this._filters = {};
    /** @type {PhotoSwipe | undefined} */

    this.pswp = undefined;
    /** @type {PhotoSwipeOptions | undefined} */

    this.options = undefined;
  }
PhotoSwipe base class that can listen and dispatch for events.
Shared by PhotoSwipe Core and PhotoSwipe Lightbox, extended by base.js