Get Human-Readable "Time Ago" in TypeScript

function is(interval: number, cycle: number) {
  return cycle >= interval ? Math.floor(cycle / interval) : 0
}
 
export function getTimeAgo(time: string | number | Date, now = Date.now()) {
  if (typeof time === 'string' || time instanceof Date) {
    time = new Date(time).getTime()
  }
 
  const secs = (now - time) / 1000
  const mins = is(60, secs)
  const hours = is(60, mins)
  const days = is(24, hours)
  const weeks = is(7, days)
  const months = is(30, days)
  const years = is(12, months)
 
  let amount = years
  let cycle = 'year'
 
  if (secs <= 1) {
    return 'just now'
  }
  if (years > 0) {
    amount = years
    cycle = 'year'
  } else if (months > 0) {
    amount = months
    cycle = 'month'
  } else if (weeks > 0) {
    amount = weeks
    cycle = 'week'
  } else if (days > 0) {
    amount = days
    cycle = 'day'
  } else if (hours > 0) {
    amount = hours
    cycle = 'hour'
  } else if (mins > 0) {
    amount = mins
    cycle = 'minute'
  } else {
    amount = secs
    cycle = 'second'
  }
 
  const v = Math.floor(amount)
 
  return `${v === 1 ? (amount === hours ? 'an' : 'a') : v} ${cycle}${v > 1 ? 's' : ''} ago`
}

import { getTimeAgo } from './time-ago'
 
getTimeAgo(new Date(Date.now() - 1000 * 60)) // → "a minute ago"
getTimeAgo(Date.now() - 1000 * 60 * 60 * 5)  // → "5 hours ago"
getTimeAgo('2024-05-18T12:00:00Z')           // → "1 year ago"