利用Data算时间

距离元旦的写法1

 function getLeftTime(){
    let a = new Date('2022-01-01 00:00:00').getTime()
    let b = Date.now()
    let c = Math.abs(b-a)
    let day = Math.floor(c/(24*3600*1000))
    c = c%(24*3600*1000)
    let hour = Math.floor(c/(3600*1000))
    c = c%(3600*1000)
    let minute =Math.floor(c/(60*1000))
    c = c%(60*1000)
    let second = Math.floor(c/1000)
   return {day,hour,minute,second}
  }
  let obj = getLeftTime()
  console.log(`距离元旦还剩${obj.day}天，${obj.hour}小时，${obj.minute}分，${obj.second}秒`)

距离元旦的写法2

function getLeftTime(data){
  let a = new Date(data).getTime()
  let b = Date.now()
  let c = Math.abs(b-a)
  let day = Math.floor(c/(24*3600*1000))
  let d = c%(24*3600*1000)
  let hour = Math.floor(d/(3600*1000))
  let e = d%(3600*1000)
  let minute = Math.floor(e/(60*1000))
  let f = e%(60*1000)
  let second = Math.floor(f/1000)
  return {day,hour,minute,second}
}
let obj = getLeftTime('2022-01-01 00:00:00')
console.log(`距离元旦还剩${obj.day}天，${obj.hour}小时，${obj.minute}分，${obj.second}秒`)

明年的今天是什么时候

 function getDayOfNextYear(){
   let newday = Date.now()+365*24*3600*1000
   let lastDay = new Date(newday).getDay()
    switch(lastDay){
     case 0:
      return '日';break;
   
     case 1:
     return '一';break;
     case 2:
     return '二';break;
     case 3:
     return '三';break;
     case 4:
     return '四';break;
     case 5:
     return '五';break;
     default:
     return '六';
     }
  
 }
 let obj =getDayOfNextYear()
 console.log('明年的今天是星期'+ obj)

距离某个时间段多少时间

function formatDate(val){
  let newDate = parseInt(Date.now()/1000)
  let lastDate =parseInt(new Date(val).getTime()/1000)
  let dap = newDate - lastDate
   switch(true){
   case dap<60:
     return `刚刚`;break;
   case dap<3600:
     return `${parseInt(dap/60)}分钟前`;break;
   case dap<(24*3600):
     return `${Math.floor(dap/3600)}个小时前`;break;
   default:
     return `${Math.floor(dap/(24*3600))}天前`;
 }
}
console.log(formatDate('2021-11-17 15:9:00'))