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 datePivot (date,
  { years = 0, months = 0, days = 0, hours = 0, minutes = 0, seconds = 0, milliseconds = 0 }) {
  return new Date(
    date.getFullYear() + years,
    date.getMonth() + months,
    date.getDate() + days,
    date.getHours() + hours,
    date.getMinutes() + minutes,
    date.getSeconds() + seconds,
    date.getMilliseconds() + milliseconds
  )
}

export const dayMonthYear = when => new Date(when).toISOString().slice(0, 10)

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'
  }
}

export const sleep = (ms) => new Promise((resolve, reject) => setTimeout(resolve, ms))