Knowing the start time and the total number of seconds, we have calculated the countdown of hours, minutes and seconds. Use TS

1. Knowing the start time and the total number of seconds, we have calculated the countdown of hours, minutes and seconds. TS;
2. The output is 24 br 24 14 50, and what I want to achieve is a countdown to it;
countdown

      <p class="groupText_2"><b -sharphour>00</b>:<b -sharpminute>00</b>:<b -sharpsecond>00</b>
      
      TS:
      //DOMJSDOM,HTML-sharphour/-sharpminute/-sharpsecond
      @ViewChild("hour") hour: ElementRef;
      @ViewChild("minute") minute: ElementRef;
      @ViewChild("second") second: ElementRef;
      
      
      var secondTime = 87890;// 
      var minuteTime = 0;// 
      var hourTime = 0;// 
      if (secondTime > 60) {//60
        //60
        minuteTime = Math.floor(secondTime / 60);
        //
        secondTime = Math.floor(secondTime % 60);
        //60
        if (minuteTime > 60) {
          //60
          hourTime = Math.floor(minuteTime / 60);
          //60
          minuteTime = Math.floor(minuteTime % 60);
        }
      }
      var resultTime = "" + Math.floor(secondTime);
      if (minuteTime > 0) {
        resultTime = "" + Math.floor(minuteTime) + ":" + resultTime;
      }
      if (hourTime > 0) {
        resultTime = "" + Math.floor(hourTime) + ":" + resultTime;
      }
      console.log(resultTime);
      // 
      this.second.nativeElement.innerHTML = Math.floor(secondTime);
      //
      this.minute.nativeElement.innerHTML = Math.floor(minuteTime);
      //
      this.hour.nativeElement.innerHTML = Math.floor(hourTime);

this.secondTime = 87900; this.interval = setInterval(() => { if(this.secondTime > 60){ this.secondTime--; var secondTime = 0; // var minuteTime = 0;// var hourTime = 0;// //60 if (this.secondTime > 60) { //60 minuteTime = Math.floor(this.secondTime / 60); // secondTime = Math.floor(this.secondTime % 60); //60 if (minuteTime > 60) { //60 hourTime = Math.floor(minuteTime / 60); //60 minuteTime = Math.floor(minuteTime % 60); } } // this.second.nativeElement.innerHTML = Math.floor(secondTime); // this.minute.nativeElement.innerHTML = Math.floor(minuteTime); // this.hour.nativeElement.innerHTML = Math.floor(hourTime); } else { this.alertPri.presentToast(''); // this.second.nativeElement.innerHTML = '00'; // this.minute.nativeElement.innerHTML = '00'; // this.hour.nativeElement.innerHTML = '00'; clearInterval(this.interval); } },1000) : this.countTime = () => { var date = new Date(); var now = date.getTime(); var endDate = new Date("2018-12-6 11:00:00"); var end = endDate.getTime(); this.leftTime = end - now; var d, h, m, s, ms; if(this.leftTime >= 0) { // d = Math.floor(leftTime / 1000 / 60 / 60 / 24); h = Math.floor(this.leftTime / 1000 / 60 / 60); m = Math.floor(this.leftTime / 1000 / 60 % 60); s = Math.floor(this.leftTime / 1000 % 60); ms = Math.floor(this.leftTime % 1000); if(ms < 100) { ms = "0" + ms; } if(s < 10) { s = "0" + s; } if(m < 10) { m = "0" + m; } if(h < 10) { h = "0" + h; } this.hour.nativeElement.innerHTML = h; this.minute.nativeElement.innerHTML = m; this.second.nativeElement.innerHTML = s; } } setInterval(this.countTime, 50); if(this.leftTime < 0){ //this.alertService.presentToast(''); clearInterval(this.countTime); this.hour.nativeElement.innerHTML = '00'; this.minute.nativeElement.innerHTML = '00'; this.second.nativeElement.innerHTML = '00'; }