import { NgZone } from '@angular/core';
import { Observable } from 'rxjs';
export declare const FOCUSABLE_ELEMENTS_SELECTOR: string;
/**
 * Returns first and last focusable elements inside of a given element based on specific CSS selector
 */
export declare function getFocusableBoundaryElements(element: HTMLElement): HTMLElement[];
/**
 * Function that enforces browser focus to be trapped inside a DOM element.
 *
 * Works only for clicks inside the element and navigation with 'Tab', ignoring clicks outside of the element
 *
 * @param zone Angular zone
 * @param element The element around which focus will be trapped inside
 * @param stopFocusTrap$ The observable stream. When completed the focus trap will clean up listeners
 * and free internal resources
 * @param refocusOnClick Put the focus back to the last focused element whenever a click occurs on element (default to
 * false)
 */
export declare const ngbFocusTrap: (zone: NgZone, element: HTMLElement, stopFocusTrap$: Observable<any>, refocusOnClick?: boolean) => void;