在addEventListener更新React状态，渲染界面

useEffect(() => {
    document.addEventListener('visibilitychange', log);
  }, []);

 const log = async () => {
    const currentTime = moment(Date.now()).format('YYYY-MM-DD HH:mm:ss');
    if (document.visibilityState == 'hidden') {
      leaveStartTime = currentTime;
      document.title = '离开';
    }
    if (document.visibilityState == 'visible') {
      setLeaveTime(prevLeaveTime => {
        return [...prevLeaveTime, { leaveStartTime, endTime: currentTime }];
      });
     
      document.title = '回来';
    }
  };