Relative time ago with native Intl.RelativeTimeFormat in JS

timeago.js

/**
 * From: https://blog.webdevsimplified.com/2020-07/relative-time-format/
 */

const formatter = new Intl.RelativeTimeFormat(undefined, {
  numeric: 'auto'
})

const DIVISIONS = [
  { amount: 60, name: 'seconds' },
  { amount: 60, name: 'minutes' },
  { amount: 24, name: 'hours' },
  { amount: 7, name: 'days' },
  { amount: 4.34524, name: 'weeks' },
  { amount: 12, name: 'months' },
  { amount: Number.POSITIVE_INFINITY, name: 'years' }
]

function formatTimeAgo(date) {
  let duration = (date - new Date()) / 1000

  for (let i = 0; i <= DIVISIONS.length; i++) {
    const division = DIVISIONS[i]
    if (Math.abs(duration) < division.amount) {
      return formatter.format(Math.round(duration), division.name)
    }
    duration /= division.amount
  }
}