JavaScript seconds to time string with format hh:mm:ss

Question

I want to convert a duration of time, i.e., number of seconds to colon-separated time string (hh:mm:ss)

I found some useful answers here but they all talk about conv

Answer 1

I like the first answer. There some optimisations:

• source data is a Number. additional calculations is not needed.

• much excess computing

Result code:

Number.prototype.toHHMMSS = function () {
    var seconds = Math.floor(this),
        hours = Math.floor(seconds / 3600);
    seconds -= hours*3600;
    var minutes = Math.floor(seconds / 60);
    seconds -= minutes*60;

    if (hours   < 10) {hours   = "0"+hours;}
    if (minutes < 10) {minutes = "0"+minutes;}
    if (seconds < 10) {seconds = "0"+seconds;}
    return hours+':'+minutes+':'+seconds;
}