主题的变奏。处理个位数秒的方式有点不同

seconds2time(0)  ->  "0s" 
seconds2time(59) -> "59s" 
seconds2time(60) -> "1:00" 
seconds2time(1000) -> "16:40" 
seconds2time(4000) -> "1:06:40"

function seconds2time (seconds) {
    var hours   = Math.floor(seconds / 3600);
    var minutes = Math.floor((seconds - (hours * 3600)) / 60);
    var seconds = seconds - (hours * 3600) - (minutes * 60);
    var time = "";

    if (hours != 0) {
      time = hours+":";
    }
    if (minutes != 0 || time !== "") {
      minutes = (minutes < 10 && time !== "") ? "0"+minutes : String(minutes);
      time += minutes+":";
    }
    if (time === "") {
      time = seconds+"s";
    }
    else {
      time += (seconds < 10) ? "0"+seconds : String(seconds);
    }
    return time;
}

这是我最近为MM:SS写的。它不完全符合问题，但它是一种不同的单行格式。

const time = 60 * 2 + 35; // 2 minutes, 35 seconds
const str = (~~(time / 60) + "").padStart(2, '0') + ":" + (~~((time / 60) % 1 * 60) + "").padStart(2, '0');

str // 02:35

编辑:添加这个是为了多样化，但这里最好的解决方案是下面的https://stackoverflow.com/a/25279399/639679。

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");
}

块上的字符串有一个新方法:padStart

const str = '5';
str.padStart(2, '0'); // 05

下面是一个示例用例:用4行JavaScript编写YouTube持续时间

毫秒到持续时间，简单的方法是:

// To have leading zero digits in strings.
function pad(num, size) {
    var s = num + "";
    while (s.length < size) s = "0" + s;
    return s;
}

// ms to time/duration
msToDuration = function(ms){
    var seconds = ms / 1000;
    var hh = Math.floor(seconds / 3600),
    mm = Math.floor(seconds / 60) % 60,
    ss = Math.floor(seconds) % 60,
    mss = ms % 1000;
    return pad(hh,2)+':'+pad(mm,2)+':'+pad(ss,2)+'.'+pad(mss,3);
}

它将327577转换为00:05:27.577。

更新

另一种不同场景的方法:

toHHMMSS = function (n) {
    var sep = ':',
        n = parseFloat(n),
        sss = parseInt((n % 1)*1000),
        hh = parseInt(n / 3600);
    n %= 3600;
    var mm = parseInt(n / 60),
        ss = parseInt(n % 60);
    return pad(hh,2)+sep+pad(mm,2)+sep+pad(ss,2)+'.'+pad(sss,3);
    function pad(num, size) {
        var str = num + "";
        while (str.length < size) str = "0" + str;
        return str;
    }
}

toHHMMSS(6315.077) // Return 01:45:15.077

/**
 * Formats seconds (number) to H:i:s format.
 * 00:12:00
 *
 * When "short" option is set to true, will return:
 * 0:50
 * 2:00
 * 12:00
 * 1:00:24
 * 10:00:00
 */
export default function formatTimeHIS (seconds, { short = false } = {}) {
  const pad = num => num < 10 ? `0${num}` : num

  const H = pad(Math.floor(seconds / 3600))
  const i = pad(Math.floor(seconds % 3600 / 60))
  const s = pad(seconds % 60)

  if (short) {
    let result = ''
    if (H > 0) result += `${+H}:`
    result += `${H > 0 ? i : +i}:${s}`
    return result
  } else {
    return `${H}:${i}:${s}`
  }
}