Javascript Number formatAsTime()

Number.prototype.formatAsTime = function() {
 var secs = Math.floor(this);
 if (secs < 0) {
  return "Indefinite";
 } else if (secs === 0) {
  return "0s";
 }
 var days = Math.floor(secs / 86400);
 var hours = Math.floor((secs % 86400) / 3600);
 var minutes = Math.floor((secs % 3600) / 60);
 var seconds = Math.floor(secs % 60);
 var str = "";
 if (days > 0) {
  str += days + "d ";
 }
 if (hours > 0) {
  str += hours + "h ";
 }
 if (minutes > 0) {
  str += minutes + "m ";
 }
 if (seconds > 0) {
  str += seconds + "s";
 }
 return str;/*from  w  w  w .ja  va 2s .  co  m*/
};
Number.prototype.tidyDecimal = function(n) {
 return Math.abs(this.toFixed(n));
};
Number.prototype.toEm = function() {
 return (this/12).tidyDecimal(3);
};