/**
 * Gets the destination for a portal given the node and a user-specified portal prop.
 * If a portal prop is not `undefined`, it is used as the destination.
 */
export declare function getPortalDestination(node: HTMLElement, portalProp: string | HTMLElement | undefined | null): string | HTMLElement | null;
export declare function isOrContainsTarget(node: HTMLElement, target: Element): boolean;
export declare function getOwnerDocument(el: Element | null | undefined): Document;