獲取某年第幾周

    isLeapYear (year) {
      return (year % 400 == 0) || (year % 4 == 0 && year % 100 != 0)
    },
    getMonthDays (year, month) {
      return [31, null, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31][month] || (this.isLeapYear(year) ? 29 : 28)
    },
    getWeekNumber (date) {
      var now = new Date(date),
        year = now.getFullYear(),
        month = now.getMonth(),
        days = now.getDate()
      for (var i = 0; i < month; i++) {
        days += this.getMonthDays(year, i)
      }
      var yearFirstDay = new Date(year, 0, 1).getDay() || 7
      var week = null
      if (yearFirstDay == 1) {
        week = Math.ceil(days / yearFirstDay)
      } else {
        days -= (7 - yearFirstDay + 1)
        week = Math.ceil(days / 7) + 1
      }
      console.log(new Date(year, 0, 1).getDay())
      return week
    },