export declare function isBrowserIE(): boolean;
export declare function isBrowserEdge(): boolean;
export declare function isBrowserSafari(): boolean;
export declare function isBrowserChrome(): boolean;
export declare function isBrowserFirefox(): boolean;
export declare function isIOSUserAgent(): boolean;
export declare function getTabIndex(el: HTMLElement | null): string | null;
export declare function getScrollbarWidth(): number | null;
export declare function isInvisibleScrollbar(): boolean;