js获取昨天，最近7天，最近30天通用方法

function formatDate (val) {
  // 格式化时间
  let start = new Date(val)
  let y = start.getFullYear()
  let m = (start.getMonth() + 1) > 10 ? (start.getMonth() + 1) : '0' + (start.getMonth() + 1)
  let d = start.getDate() > 10 ? start.getDate() : '0' + start.getDate()
  return y + '-' + m + '-' + d
}

function mistiming (sDate1, sDate2) {
  // 计算开始和结束的时间差
  let aDate, oDate1, oDate2, iDays
  aDate = sDate1.split('-')
  oDate1 = new Date(aDate[1] + '-' + aDate[2] + '-' + aDate[0])
  aDate = sDate2.split('-')
  oDate2 = new Date(aDate[1] + '-' + aDate[2] + '-' + aDate[0])
  iDays = parseInt(Math.abs(oDate1 - oDate2) / 1000 / 60 / 60 / 24)
  return iDays + 1
}

function countDate (start, end) {
  // 判断开始和结束之间的时间差是否在90天内
  let days = mistiming(start, end)
  let stateT = days > 90 ? Boolean(0) : Boolean(1)
  return {
    state: stateT,
    day: days
  }
}46 
function timeForMat (count) {
  // 拼接时间
  let time1 = new Date()
  time1.setTime(time1.getTime() - (24 * 60 * 60 * 1000))
  let Y1 = time1.getFullYear()
  let M1 = ((time1.getMonth() + 1) > 10 ? (time1.getMonth() + 1) : '0' + (time1.getMonth() + 1))
  let D1 = (time1.getDate() > 10 ? time1.getDate() : '0' + time1.getDate())
  let timer1 = Y1 + '-' + M1 + '-' + D1 // 当前时间
  let time2 = new Date()
  time2.setTime(time2.getTime() - (24 * 60 * 60 * 1000 * count))
  let Y2 = time2.getFullYear()
  let M2 = ((time2.getMonth() + 1) > 10 ? (time2.getMonth() + 1) : '0' + (time2.getMonth() + 1))
  let D2 = (time2.getDate() > 10 ? time2.getDate() : '0' + time2.getDate())
  let timer2 = Y2 + '-' + M2 + '-' + D2 // 之前的7天或者30天
  return {
    t1: timer1,
    t2: timer2
  }
}

function yesterday (start, end) {
  // 校验是不是选择的昨天
  let timer = timeForMat(1)
  return timer
}

function sevenDays () {
  // 获取最近7天
  let timer = timeForMat(7)
  return timer
}

function thirtyDays () {
  // 获取最近30天
  let timer = timeForMat(30)
  return timer
}