/** Component used to observe intersections between viewport and elements. */
declare class ViewportIntersectionObserver {
    /** Instance of ViewportIntersectionObserver. */
    private static instance;
    /** Intersection observer. */
    private observer;
    /** Map of handlers that are called when intersection between viewport and element changes. */
    private elements;
    /**
     * Creates new instance.
     */
    private constructor();
    /**
     * Starts to observe intersection changes between passed element and viewport.
     * @param element Element.
     * @param handler Function to be called when intersection between element and viewport changes.
     */
    static observe(element: Element, handler: (isIntersecting: boolean) => void): void;
    /**
     * Stops to observe intersection changes between passed element and viewport.
     * @param element Element.
     */
    static unobserve(element: Element): void;
    /**
     * Callback for IntersectionObserver (called when intersection between viewport and some observed element(s) changes).
     * @param entries Intersection observer entries.
     */
    private intersectionObserverCallback;
    /**
     * Returns instance of ViewportIntersectionObserver (this method should be used instead of constructor).
     * @returns Instance of ViewportIntersectionObserver.
     */
    private static getInstance;
}
export default ViewportIntersectionObserver;