如果你是在处理视频长度，这个版本的公认答案会让它看起来更漂亮:

1:37:40(1小时/ 37分钟/ 40秒)

1:00(1分钟)

2:20(2分20秒)

String.prototype.toHHMMSS = function () {
  var sec_num = parseInt(this, 10); // don't forget the second param
  var hours   = Math.floor(sec_num / 3600);
  var minutes = Math.floor((sec_num - (hours * 3600)) / 60);
  var seconds = sec_num - (hours * 3600) - (minutes * 60);

  var hourSeparator = ':';
  var minuteSeparator = ':';

  if(hours == 0){hours = '';hourSeparator = '';}
  if (minutes < 10 && hours != 0) {minutes = "0"+minutes;}
  if (seconds < 10) {seconds = "0"+seconds;}
  var time = hours+hourSeparator+minutes+minuteSeparator+seconds;
  return time;
}

function secondsToTime(secs)
{
    var hours = Math.floor(secs / (60 * 60));

    var divisor_for_minutes = secs % (60 * 60);
    var minutes = Math.floor(divisor_for_minutes / 60);

    var divisor_for_seconds = divisor_for_minutes % 60;
    var seconds = Math.ceil(divisor_for_seconds);

    if(hours >= 12)
    {
     var m= 'pm' ;
     }
     else
     {
         var m='am'
     }
     if(hours-12 >0)
     {
            var hrs = hours-12;
     }
     else if(hours-12 <0)
     {
            var hrs = hours;
     }
    var obj = {
        "h": hrs,
        "m": minutes,
        "s": seconds,
        "a":m
    };


    return obj;
}
var d = new Date();
var n = d.getHours();
var hms = d.getHours()+':'+d.getMinutes()+':'+d.getSeconds();   // your input string
var a = hms.split(':'); // split it at the colons

// minutes are worth 60 seconds. Hours are worth 60 minutes.
var seconds = (+a[0]) * 60 * 60 + (+a[1]) * 60 + (+a[2]); 




console.log(seconds);
console.log(secondsToTime(seconds))

https://jsfiddle.net/jithinksoft/9x6z4sdt/

这是最简单的方法。

new Date(sec * 1000).toISOString().substr(11, 8)

我是这样做的。它似乎工作得相当好，而且非常紧凑。(不过，它使用了很多三元操作符)

function formatTime(seconds) {
  var hh = Math.floor(seconds / 3600),
    mm = Math.floor(seconds / 60) % 60,
    ss = Math.floor(seconds) % 60;
  return (hh ? (hh < 10 ? "0" : "") + hh + ":" : "") + ((mm < 10) && hh ? "0" : "") + mm + ":" + (ss < 10 ? "0" : "") + ss
}

.．.对于格式化字符串…

String.prototype.toHHMMSS = function() {
  formatTime(parseInt(this, 10))
};

            //secondsToTime();
            var t = wachttijd_sec; // your seconds
            var hour = Math.floor(t/3600);
            if(hour < 10){
                hour = '0'+hour;
            }
            var time = hour+':'+('0'+Math.floor(t/60)%60).slice(-2)+':'+('0' + t % 60).slice(-2);
            //would output: 00:00:00 > +100:00:00

即使超过24小时也能保持倒计时

我认为这是目前为止最快的性能:

var t = 34236; // your seconds
var time = ('0'+Math.floor(t/3600) % 24).slice(-2)+':'+('0'+Math.floor(t/60)%60).slice(-2)+':'+('0' + t % 60).slice(-2)
//would output: 09:30:36