dropdowns require Popper (https://popper.js.org)')\n      }\n\n      let referenceElement = this._element\n\n      if (this._config.reference === 'parent') {\n        referenceElement = parent\n      } else if (Util.isElement(this._config.reference)) {\n        referenceElement = this._config.reference\n\n        // Check if it's jQuery element\n        if (typeof this._config.reference.jquery !== 'undefined') {\n          referenceElement = this._config.reference[0]\n        }\n      }\n\n      // If boundary...