JS 根据年和周获取起止时间

getDate(){
     if(week>53){
       return
     }
     let year = 2019;
     let week = 1;
     let firstDayWeek =new Date(`${year}-01-01`).getDay();
     let firstWeekFirstDay;
     if(firstDayWeek<=3){
       firstWeekFirstDay = moment(new Date(`${year}-01-01`)).subtract(firstDayWeek, 'days').format('YYYY-MM-DD');
     }else{
       firstWeekFirstDay = moment(new Date(`${year}-01-01`)).add(7-firstDayWeek, 'days').format('YYYY-MM-DD');
     }
     let startDate = moment(firstWeekFirstDay).add(7*(week-1),'days').format('YYYY-MM-DD');
     let endDate = moment(startDate).add(6,'days').format('YYYY-MM-DD');
     console.log('startDate',startDate);
     console.log('endDate',endDate);
   }