日期默认传上个月的第一个周六与最后一周的周五

// 日期默认传上个月的第一个周六与最后一周的周五

  function getDate() {
    var date = new Date()
    var month = date.getMonth()
    var thisYear = date.getFullYear()
    if (month == 0) {  
      month = 12
      thisYear = thisYear - 1
    }  

// 上个月第一天

  var firstDay = `${thisYear}-${month}-1`

// 上个月最后一天

  var myDate = new Date(thisYear, month, 0);  
  var lastDay = thisYear + "-" + month + "-" + myDate.getDate();

// 获取上个月的第一个周六

  function getSaturday(target) {
    let now = new Date(target);
    let now_day= now.getDay();
    let now_time = now.getTime();
    let result = [6]
    let time =  new　Date(result.map(i => (new Date(now_time + 24*60*60*1000*(i - now_day)))) )
    let date = time.getFullYear() + "-" + (time.getMonth() + 1) + "-" + time.getDate()
    return date
  }
  var firstSaturday = getSaturday(firstDay)

// 获取上个月最后一天位于的当周周五

  function getFriday(target) {
    let now = new Date(target);
    let now_day= now.getDay();
    let now_time = now.getTime();
    let result = [5]
    return new　Date(result.map(i => (new Date(now_time + 24*60*60*1000*(i - now_day)))))
  }

// 获取上个月最后一周的周五

  var FridayDate = getFriday(lastDay)
  var thisMonth = FridayDate.getMonth() + 1
  if (month === thisMonth) {
    var lastFriday = FridayDate.getFullYear() + '-' + (FridayDate.getMonth() + 1) + '-' + FridayDate.getDate()
  } else {
  // 如果上个月的最后一天在本月,则减7天
    var newDate = new Date(FridayDate.getTime() - 7*24*60*60*1000);
    var lastFriday = newDate.getFullYear() + "-" + (newDate.getMonth() + 1) + "-" + newDate.getDate();
  }

  var aboveDate = {}
  aboveDate.firstSaturday = firstSaturday
  aboveDate.lastFriday = lastFriday
  return aboveDate
}