小程序 未支付订单倒计时

下面的是针对 多个 未付款订单倒计划：
在传入orderList的地方调用countdown方法

countdown: function(){
    var step = 1000;
    var that = this;
    var timer = setInterval(function(){
      for (let i = 0; i < that.data.orderList.length; i++) {
        if (that.data.orderList[i].orderStatus != 'UNPAID') {
          continue;
        }
        var restTime = that.data.orderList[i].leftTime;
        if (restTime >= 0) {
          var timeSeconds = that.formatTime(restTime);
          that.data.orderList[i].showTime = timeSeconds;
          that.data.orderList[i].leftTime = restTime - step;
        } else {
          that.data.orderList[i].orderStatus = 'CANCELLED';//前台修改订单状态
          that.data.orderList[i].leftTime = 0;
          clearInterval(timer);//清空计时
        }
        that.setData({
          orderList: that.data.orderList
        });
      }
    }, step);
    
  },

  formatTime: function (s) {
    var min = Math.floor(s / 60/1000) % 60;
    var sec = parseInt((s /1000 % 60).toFixed(2));
    min = min < 10 ? '0'+min : min;
    sec = sec < 10 ? '0' + sec: sec;
    return min + ':' + sec
  },