import * as React from "react";
import { Booleanish, EventKeys } 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): EventKeys;
export declare const dataAttr: (condition: boolean | undefined) => Booleanish;
export declare const ariaAttr: (condition: boolean | undefined) => true | undefined;
export declare const getDocument: (node?: HTMLElement | null | undefined) => Document | null;
export declare const cx: (...classNames: any[]) => string;
export declare function getActiveElement(node?: HTMLElement): HTMLElement;
export declare function contains(parent: HTMLElement, child: HTMLElement): boolean;