Use momentJs to make a countdown component (example code)

<template>
    <div class="table-right flex-a-center">
        <div class="time-text">
            <span class="timeTextSpan" v-for="item,index of h" >{{item}}</span>
            <span class="timeTextSpan1" >: </span>
            <span class="timeTextSpan" v-for="item,index of m" >{{item}}</span>
            <span class="timeTextSpan1" >: </span>
            <span class="timeTextSpan" v-for="item,index of s" >{{item}}</span>
        </div>
    </div>
</template>

<script>
import moment from 'moment'
export default {
  props: {
    endTime: { }, //Last received time 2021-12-17 16:29:20
  },
  data() {
    //Store data here return {
      h:'00',
      m:'00',
      s:'00',
      timer:null
    };
  },
  watch:
    endTime: {
      handler(e) {
        if (e) {
          let self = this
          clearInterval(this.timer)
          this.timer = setInterval(function(){self.init()},1000)
        }
      },
      deep: true,
      immediate: true
    }
  },
  mounted() {
    let self = this
    self.init()
    clearInterval(this.timer)
    this.timer = setInterval(function(){self.init()},1000)
  },
  //Method collection methods: {
    init(){
        let time = moment(this.endTime).diff(moment())
        if(time <= 0){
          clearInterval(this.timer)
          this.onOver()
          return
        }
        let t = time / 1000;
        let d = Math.floor(t / (24 * 3600)); //Remaining days, you can make up for it if necessary let h = Math.floor((t - 24 * 3600 * d) / 3600) + d*24; //No days needed, convert days into hours let _h = Math.floor((t - 24 * 3600 * d) / 3600) //Keep the days and get the hours let m = Math.floor((t - 24 * 3600 * d - _h * 3600) / 60);
        let s = Math.floor((t - 24 * 3600 * d - _h * 3600 - m * 60));
       
        this.h = String(h).length == 1? '0'+String(h):String(h)
        this.m = String(m).length == 1? '0'+String(m):String(m)
        this.s = String(s).length == 1? '0'+String(s):String(s)
    },
    onOver() {
      this.$emit('over') //Callback when countdown ends}
 
  },
  beforeDestroy(){
    this.timer = null
    clearInterval(this.timer)
  }
}
</script>
<style lang='less' scoped>
@import url("@/assets/css/supplier.less");
 

  .table-right {
    font-size: 12px;
    color: #757e8a;
    .timeTextSpan{
      display: inline-block;
      width: 14px;
      height: 22px;
      text-align: center;
      background: #F1F0F0;
      border-radius: 2px;
      margin-right: 2px;
      font-size: 16px;
      color: #ff8a2b;
      font-weight: bold;
    }
    .timeTextSpan1{
      display: inline-block;
      width: 14px;
      text-align: center;
      vertical-align: bottom;
      color:#202D40;
      font-size: 16px;
      font-weight: bold;
    }
   
    .time-text {
      margin-left: 10px;
    }
  }
</style>