/**
 * When a visitor is not producing any events (e.g. because they are reading an article or watching a video), we don’t know if they are still on the page. This might skew page statistics, e.g. time on page value. Heartbeat timer allows us to determine how much time visitors spend on a page by sending heartbeats to the Tracker as long as the page is in focus.
 */
export declare function enableHeartBeatTimer(delays?: number[]): void;
/**
 * Disables sending heartbeats if they were previously enabled by "enableHeartBeatTimer" function.
 */
export declare function disableHeartBeatTimer(): void;