微信小程序时间戳与日期格式转换及倒计时实现

//时间的格式为 xxxx-xx-xx 即 年-月-日， 小程序picker中经常可以用到
//昨天的时间
var day1 = new Date();
day1.setTime(day1.getTime()-24*60*60*1000);
var s1 = day1.getFullYear()+"-" + (day1.getMonth()+1) + "-" + day1.getDate();
//今天的时间
var day2 = new Date();
day2.setTime(day2.getTime());
var s2 = day2.getFullYear()+"-" + (day2.getMonth()+1) + "-" + day2.getDate();
//明天的时间
var day3 = new Date();
day3.setTime(day3.getTime()+24*60*60*1000);
var s3 = day3.getFullYear()+"-" + (day3.getMonth()+1) + "-" + day3.getDate();

 that.getDeadline("2025-04-16 17:35:15");
getDeadline: function (time) {
    var date1 = new Date(time + ":000");
    var timeStamp1 = date1.getTime();
    var date2 = new Date(timeStamp1);
    date2.setTime(date1.getTime() - 24 * 60 * 60 * 1000);
    var year = date2.getFullYear()
    var month = date2.getMonth() + 1
    if (month < 10) {
      month = "0" + month
    }
    var day = date2.getDate()
    if (day < 10) {
      day = "0" + day
    }
    var hour = date2.getHours()
    if (hour < 10) {
      hour = "0" + hour
    }
    var minite = date2.getMinutes();
    if (minite < 10) {
      minite = "0" + minite
    }
    var second = date2.getSeconds();
    if (second < 10) {
      second = "0" + second
    }
    var time2 = year + "-" + month + "-" + day + ' ' + hour + ":" + minite + ":" + second;
    return time2;
  },

   var date = new Date("2022-12-04 17:15:53:555");
    // 有三种方式获取
    var time1 = date.getTime();
    var time2 = date.valueOf();
    var time3 = Date.parse(date);
    console.log(time1); //1670145353555
    console.log(time2); //1670145353555
    console.log(time3); //1670145353000

var time = '2020-04-01 00:00:00';
var repTime = time.replace(/-/g, '/');//用正则主要是把“2020-04-01 00:00:00'”转换成“2020/04/01 00:00:00'”兼容ios
console.log("返回时间：" + repTime);
var timeTamp = Date.parse(repTime);
console.log("返回时间戳：" + timeTamp)

<view class="TimeSeond">{{timeSecond}}</view>

Page({
  data: {
    timeSecond: '', //倒计时
  },
  onLoad() {
    this.timeCountdown();
  },
  timeCountdown() {
    var that = this
    var timeStampCur = new Date().getTime();
    //30分钟前
    var timeStampBefore = timeStampCur - 30 * 60 * 1000;
    if (timeStampCur > timeStampBefore) {
      var timeStampInterval = timeStampCur - timeStampBefore
      var hours = parseInt((timeStampInterval % (24 * 60 * 60 * 1000)) / (60 * 60 * 1000));
      var minutes = parseInt((timeStampInterval % (60 * 60 * 1000)) / (60 * 1000));
      var seconds = parseInt((timeStampInterval % (60 * 1000)) / 1000);
      var timeNum = setInterval(function () {
        timeStampInterval = timeStampInterval - 1000
        hours = parseInt((timeStampInterval % (24 * 60 * 60 * 1000)) / (60 * 60 * 1000));
        minutes = parseInt((timeStampInterval % (60 * 60 * 1000)) / (60 * 1000));
        seconds = parseInt((timeStampInterval % (60 * 1000)) / 1000);
        if (timeStampInterval < 1) {
          that.setData({
            timeSecond: '00:00:00'
          })
          clearInterval(timeNum)
          return false
        }
        hours = hours > 9 ? hours : '0' + hours
        minutes = minutes > 9 ? minutes : '0' + minutes
        seconds = seconds > 9 ? seconds : '0' + seconds
        that.setData({
          timeSecond: hours + ':' + minutes + ':' + seconds
        })
      }, 1000)
    } else {
      that.setData({
        timeSecond: '00:00:00'
      })
    }
  },
})