js获取当前日期是一年的第几周

    getWeekOnYears(val) {
      const year = dayjs(val).year() //获取年
      const month = dayjs(val).month() + 1 //获取月
      const day = dayjs(val).date() //获取天
      const isLeapYear = (year % 400 === 0) || (year % 4 === 0 && year % 100 !== 0) //判断是否为闰年
      const second = isLeapYear ? 29 : 28
      const monthList = [31, second, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31].splice(0, month - 1) //获取月份数组
      let currentDays; //当前日期天数
      let currentWeek; //当前周数
      //计算天数
      currentDays = month === 1 ? day : (monthList.reduce((t, v) => {
        return t + v
      }, 0)) + day
      //计算是第几周
      currentWeek = currentDays % 7 === 0 ? currentDays / 7 : Math.ceil(currentDays / 7)
      return currentWeek
    },