Vue中 获取当前时间并实时刷新

<template>
  <div>
    {{nowDate}}{{nowWeek}}{{nowTime}}
  </div>
</template>
<script>
export default {
  data(){
    return {
      nowDate: "",    // 当前日期
      nowTime: "",    // 当前时间
      nowWeek: ""     // 当前星期
    }
  },
  methods:{
    dealWithTime(data) { // 获取当前时间
      let formatDateTime;
      let Y = data.getFullYear();
      let M = data.getMonth() + 1;
      let D = data.getDate();
      let H = data.getHours();
      let Min = data.getMinutes();
      let S = data.getSeconds();
      let W = data.getDay();
      H = H < 10 ? "0" + H : H;
      Min = Min < 10 ? "0" + Min : Min;
      S = S < 10 ? "0" + S : S;
      switch (W) {
        case 0:
          W = "日";
          break;
        case 1:
          W = "一";
          break;
        case 2:
          W = "二";
          break;
        case 3:
          W = "三";
          break;
        case 4:
          W = "四";
          break;
        case 5:
          W = "五";
          break;
        case 6:
          W = "六";
          break;
        default:
          break;
      }
      this.nowDate = Y + "年" + M + "月" + D + "日 ";
      this.nowWeek = "周" + W ; 
      this.nowTime = H + ":" + Min + ":" + S;
      // formatDateTime = Y + "年" + M + "月" + D + "日 " + " 周" +W + H + ":" + Min + ":" + S;
    },
  },
  mounted() { 
    // 页面加载完后显示当前时间
    this.dealWithTime(new Date())
    // 定时刷新时间
    this.timer = setInterval(()=> {
       this.dealWithTime(new Date()) // 修改数据date
    }, 500)
  }, 
  destroyed() {
    if (this.timer) {  // 注意在vue实例销毁前，清除我们的定时器
      clearInterval(this.timer);
    }
  }
}
</script>
<style lang="scss" scope>
</style>

var d = new Date();
var d = new Date(milliseconds);
var d = new Date(dateString);
var d = new Date(year, month, day, hours, minutes, seconds, milliseconds);