translate ordinal suffixes

Another quick one today. Ever needed to dynamically add ordinal suffixes to your numbers? For example make 23 → 23rd or 41 → 41st?

A very common solution that pops up on StackOverflow, and which you can also find in some well-known libraries, e.g. Shopify, is this snippet

export const ordinal = (num) => {
  const suffix = ['th', 'st', 'nd', 'rd']
  const value = val % 100

  return val + (suffix[(value - 20) % 10] || suffix[value] || suffix[0])
}

But this doesn’t scale that nicely when you want to localize these suffixes. So let’s look at the beloved (but maybe not that known) Intl API, namely its Intl.PluralRules interface.

const enOrdinalRules = new Intl.PluralRules('en', {type: 'ordinal'})
const suffixes = {
  one: 'st',
  two: 'nd',
  few: 'rd',
  other: 'th'
}

function ordinal(number: number): string {
    const category = enOrdinalRules.select(number)
    const suffix = suffixes[category]
    return number + suffix
}

const test = Array(201)
  .fill()
  .map((_, idx) => idx - 100)
  .map(ordinal)
  .join(' ')

I won’t log it all onto the page, but open your Console to see the results! That’s all 🖖