Time Ago.js

time-ago.ts

const oneDay = 60 * 60 * 24 * 1000

const weekDays = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']

const getTime = (date: Date) => {
  const amPM = date.getHours() > 12 ? 'PM' : 'AM'
  const time = [date.getHours() % 12, String(date.getMinutes()).padStart(2, '0')].join(':')
  return time + ' ' + amPM
}

const ordinal = (i) => {
  const j = i % 10,
    k = i % 100
  if (j == 1 && k != 11) {
    return i + 'st'
  }
  if (j == 2 && k != 12) {
    return i + 'nd'
  }
  if (j == 3 && k != 13) {
    return i + 'rd'
  }
  return i + 'th'
}

const timeAgo = (date: Date) => {
  const currentDate = new Date()

  if (date > currentDate) {
    throw new Error('errrr')
  }

  const diffInDays = (currentDate.getTime() - date.getTime()) / oneDay
  if (diffInDays < 7) {
    const time = getTime(date)
    const actualDays = currentDate.getDay() - date.getDay()
    const dayOfWeek = date.getDay() % 7
    if (actualDays == 0) {
      return 'Today, ' + time
    } else if (actualDays == 1) {
      return 'Yesterday, ' + time
    } else {
      return weekDays[dayOfWeek] + ', ' + time
    }
  }

  return [months[date.getMonth()], ordinal(date.getDate())].join(' ')
}

export default timeAgo