Duration in seconds to "h:mm:ss" format

toTimeFormat.js

Number.prototype.toTimeFormat = function() {
	var d = [Math.floor(this / 60 % 60), Math.floor(this % 60)],
		h = Math.floor(this / 60 / 60 % 60);
	d = d.map(function(n) {return n >= 10 ? n : "0" + n});
	h && d.unshift(h);
	return d.join(":");
};

// using
var duration = 12345;
console.log(duration.toTimeFormat());