export declare const PRESERVE_TABINDEX_CLASSNAME = "md-nav-preserve-tabindex";
type Options = {
    /**
     * whether only tabbable children should be returned or all
     */
    includeTabbableOnly?: boolean;
    /**
     * Exclude elements with `data-preserve-tabindex` attribute and all their children
     */
    excludePreserveTabindex?: boolean;
};
/**
 * Returns all focusable child elements as an Element Array
 *
 * An element focusable if it:
 * - it is interactive element (anchor with href, button, input, textarea, select and details)
 * - it is not disabled
 * - it is not hidden
 * - it or any of its parents do not have `aria-hidden=true` attribute
 * - it or any of its parents do not have `data-preserve-tabindex` attribute or `
 *   md-nav-preserve-tabindex` class
 * - it has none empty or not "-1" tabindex, see `includeTabbableOnly` parameter
 *
 * @remarks
 * Element with 0 tabindex can be tabbed to, while elements with any tabindex value can be
 * manually focused
 *
 * @param root Element lookup starts from this element
 * @param options Options to customize the behavior
 */
export declare function getKeyboardFocusableElements<T extends HTMLElement>(root: T, options?: Options): Array<HTMLElement>;
export {};