/**
 * Interface for objects that is handling the intersection events.
 */
export interface IIntersectable {
    onIntersecting(isIntersecting: boolean): void;
}
/**
 * Observe the element for viewport intersection events.
 * @param editor
 * @param element
 * @returns callback to unobserve the element
 */
export declare function observe(intersectable: IIntersectable, element: Element): () => void;
/**
 * unobserve the element for viewport intersection events.
 * @param element the monitored html element
 */
export declare function unobserve(element: Element): void;