stacker.news/lib/time.js

export function timeSince (timeStamp) {
  const now = new Date()
  const secondsPast = (now.getTime() - timeStamp) / 1000
  if (secondsPast < 60) {
    return parseInt(secondsPast) + 's'
  }
  if (secondsPast < 3600) {
    return parseInt(secondsPast / 60) + 'm'
  }
  if (secondsPast <= 86400) {
    return parseInt(secondsPast / 3600) + 'h'
  }
  if (secondsPast > 86400) {
    const day = timeStamp.getDate()
    const month = timeStamp.toDateString().match(/ [a-zA-Z]*/)[0].replace(' ', '')
    const year = timeStamp.getFullYear() === now.getFullYear() ? '' : ' ' + timeStamp.getFullYear()
    return day + ' ' + month + year
  }

  return 'now'
}

export function timeLeft (timeStamp) {
  const now = new Date()
  const secondsPast = (timeStamp - now.getTime()) / 1000

  if (secondsPast < 0) {
    return false
  }

  if (secondsPast < 60) {
    return parseInt(secondsPast) + 's'
  }
  if (secondsPast < 3600) {
    return parseInt(secondsPast / 60) + 'm'
  }
  if (secondsPast <= 86400) {
    return parseInt(secondsPast / 3600) + 'h'
  }
  if (secondsPast > 86400) {
    return parseInt(secondsPast / (3600 * 24)) + ' days'
  }
}