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/

function formatTime(seconds) {
    return [
        parseInt(seconds / 60 / 60),
        parseInt(seconds / 60 % 60),
        parseInt(seconds % 60)
    ]
        .join(":")
        .replace(/\b(\d)\b/g, "0$1")
}

如果你知道你有多少秒，这就可以了。它还使用本机Date()对象。

function formattime(numberofseconds){    
    var zero = '0', hours, minutes, seconds, time;

    time = new Date(0, 0, 0, 0, 0, numberofseconds, 0);

    hh = time.getHours();
    mm = time.getMinutes();
    ss = time.getSeconds() 

    // Pad zero values to 00
    hh = (zero+hh).slice(-2);
    mm = (zero+mm).slice(-2);
    ss = (zero+ss).slice(-2);

    time = hh + ':' + mm + ':' + ss;
    return time; 
}

正则表达式可以用来匹配Date对象的toString()方法返回的字符串中的时间子字符串，该字符串的格式如下:“Thu Jul 05 2012 02:45:12 GMT+0100 (GMT夏令时)”。请注意，此解决方案使用自epoch以来的时间:1970年1月1日午夜。这个解决方案可以是一行代码，不过将其拆分会更容易理解。

function secondsToTime(seconds) {
    const start = new Date(1970, 1, 1, 0, 0, 0, 0).getTime();
    const end = new Date(1970, 1, 1, 0, 0, parseInt(seconds), 0).getTime();
    const duration = end - start;

    return new Date(duration).toString().replace(/.*(\d{2}:\d{2}:\d{2}).*/, "$1");
}

这很简单，

function toTimeString(seconds) {
  return (new Date(seconds * 1000)).toUTCString().match(/(\d\d:\d\d:\d\d)/)[0];
}

你可以在没有任何外部JS库的帮助下使用JS Date方法做到这一点，如下所示:

var date = new date (0); date.setSeconds (45);//指定SECONDS的值 var timeString = date.toISOString()。substring(11、19); console.log (timeString)