import React from 'react';
import { Booleanish } from './types';
/**
 * Helper to get the window object. The helper will make sure to use a cached variable
 * of "window", to avoid overhead and memory leaks in IE11.
 */
export declare const getWindow: (node?: HTMLElement | null | undefined) => Window | undefined;
export declare const isBrowser: boolean;
/**
 * Get the normalized event key across all browsers
 * @param event keyboard event
 */
export declare function normalizeEventKey(event: React.KeyboardEvent): string;
export declare const dataAttr: (condition: boolean | undefined) => Booleanish;
export declare const ariaAttr: (condition: boolean | undefined) => true | undefined;
export declare const getOwnerDocument: (node?: HTMLElement | undefined) => Document;
export declare const cx: (...classNames: any[]) => string;
export declare function addDomEvent(target: EventTarget, eventName: string, handler: EventListener, options?: AddEventListenerOptions): () => void;
export declare function getEventWindow(event: Event): typeof globalThis;
export declare function isElement(el: any): el is Element;
export declare function isHTMLElement(el: any): el is HTMLElement;
export declare function contains(parent: HTMLElement | null, child: HTMLElement): boolean;
export declare function getActiveElement(node?: HTMLElement): HTMLElement;
export declare function getRelatedTarget(event: Pick<FocusEvent, 'relatedTarget' | 'target' | 'currentTarget'>): HTMLElement;