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
   }
 }
 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
 }

 export {
   formatDate,
   countDate,   yesterday,
   sevenDays,
   thirtyDays
 }