NT_HIDDEN)\n    })\n  }\n\n  _removeBackdrop() {\n    if (this._backdrop) {\n      $(this._backdrop).remove()\n      this._backdrop = null\n    }\n  }\n\n  _showBackdrop(callback) {\n    const animate = $(this._element).hasClass(CLASS_NAME_FADE) ?\n      CLASS_NAME_FADE : ''\n\n    if (this._isShown && this._config.backdrop) {\n      this._backdrop = document.createElement('div')\n      this._backdrop.className = CLASS_NAME_BACKDROP\n\n      if (animate) {\n        this._backdrop.classList.add(animate)\n...