meta-server/ws/HeartBeat.js

export default class Heartbeat {
  constructor(e) {
    E(this, '_interval', null);
    E(this, 'ping', () => {
      const e = Date.now().toString();
      this.handler.ping(e);
    });
    this.handler = e;
  }
  ping() {
    const e = Date.now().toString();
    this.handler.ping(e);
  }
  start() {
    this.stop(),
      logger.debug(`Setting ping interval to ${PING_INTERVAL_MS}ms`),
      (this._interval = window.setInterval(this.ping, PING_INTERVAL_MS));
  }
  stop() {
    logger.debug('stop heartbeat'),
      this._interval && window.clearInterval(this._interval);
  }
  pong(e, t) {
    !e ||
      (typeof e == 'string' && this.handler.pong(Date.now() - Number(e), t));
  }
}