拿到今天往后 最近的 多个 周几

方法及例子如下：

比如拿到今天往后 最近的 5个 周二（不包括今天）

参数：

weekday 是周几，参数范围是 0 - 6，0 代表周日

num 是个数

startDay 是开始计算的时间，是时间戳

function getDays(weekday, num, startDay, lastResult) {
  // 判断
  if ([0, 1, 2, 3, 4, 5, 6].indexOf(weekday) === -1) {
    return 'weekday 错误'
  }
  if (num <= 0) {
    return 'num 错误'
  }
  let todayDate = new Date()
  let today =
    todayDate.getFullYear() +
    '-' +
    (todayDate.getMonth() + 1) +
    '-' +
    todayDate.getDate()
  if (startDay) {
    if (typeof startDay !== 'number') {
      return 'startDay 错误'
    }
    if (startDay < new Date(today).getTime()) {
      return 'startDay 错误'
    }
  }
  if (
    lastResult &&
    Object.prototype.toString.call(lastResult) !== '[object Array]'
  ) {
    return 'lastResult 错误'
  }
  // 正文
  let date = startDay ? new Date(startDay) : new Date()
  let day = date.getDay()
  let oneDay = 24 * 60 * 60 * 1000
  let afterDay
  let stepDays
  let result = lastResult ? lastResult : []
  if (day == weekday) {
    stepDays = 7 * oneDay
  } else if (day < weekday) {
    stepDays = (weekday - day) * oneDay
  } else if (day > weekday) {
    stepDays = (7 - day + weekday) * oneDay
  }
  afterDay = new Date(date.getTime() + stepDays)
  result.push(afterDay)
  if (--num) {
    getDays(weekday, num, afterDay.getTime(), result)
  }
  return result
}

let result = getDays(2, 5)
console.log(result)
 
/*
0: Tue Apr 12 2022 15:27:42 GMT+0800 (中国标准时间) {}
1: Tue Apr 19 2022 15:27:42 GMT+0800 (中国标准时间) {}
2: Tue Apr 26 2022 15:27:42 GMT+0800 (中国标准时间) {}
3: Tue May 03 2022 15:27:42 GMT+0800 (中国标准时间) {}
4: Tue May 10 2022 15:27:42 GMT+0800 (中国标准时间) {}
*/