Simple seconds to hh:mm:ss functions

timeLeft.js

// this has a max of 24 hrs
const timeLeft = (secs) => 
  new Date(secs * 1000)
    .toISOString()
    .substr(11, 8)
    .replace(/^([00:])*/g, '') || '0';

// this could be extended to include days
const timeLeft = (time) => {
  const hrs = Math.floor(time / 3600);
  const mins = Math.floor((time % 3600) / 60);
  const secs = Math.floor(time % 60);
  return [hrs, mins, secs]
    .map(n => n < 10 ? `0${n}` : n.toString())
    .join(':')
    .replace(/^([00:])*/g, '') || '0';
}