js获取当前周是本年的第几周

 // 获取当前日期是本年的第几周
    getYearWeek (endDate) {
      //本年的第一天
      var beginDate = new Date(endDate.getFullYear(), 0, 1);
      //星期从0-6,0代表星期天，6代表星期六
      var endWeek = endDate.getDay();
      if (endWeek == 0) endWeek = 7;
      var beginWeek = beginDate.getDay();
      if (beginWeek == 0) beginWeek = 7;
      //计算两个日期的天数差
      var millisDiff = endDate.getTime() - beginDate.getTime();
      var dayDiff = Math.floor((millisDiff + (beginWeek - endWeek) * (24 * 60 * 60 * 1000)) / 86400000);
      this.currentWeek = Math.ceil(dayDiff / 7)
      // return Math.ceil(dayDiff / 7) + 1;
    }