Intl.PluralRules() constructor

locales Optional

A string with a BCP 47 language tag or an Intl.Locale instance, or an array of such locale identifiers. The runtime's default locale is used when undefined is passed or when none of the specified locale identifiers is supported. For the general form and interpretation of the locales argument, see the parameter description on the Intl main page.

options Optional

An object containing the following properties, in the order they are retrieved (all of them are optional):

localeMatcher

The locale matching algorithm to use. Possible values are "lookup" and "best fit"; the default is "best fit". For information about this option, see Locale identification and negotiation.

type

The type to use. Possible values are:

"cardinal" (default)

For cardinal numbers (referring to the quantity of things).

"ordinal"

For ordinal number (referring to the ordering or ranking of things, e.g. "1st", "2nd", "3rd" in English).

Intl.PluralRules also supports the Intl.NumberFormat() digit options (see Intl.NumberFormat() for details):

• minimumIntegerDigits
• minimumFractionDigits
• maximumFractionDigits
• minimumSignificantDigits
• maximumSignificantDigits
• roundingPriority
• roundingIncrement
• roundingMode

These options are interpreted as if the notation option from Intl.NumberFormat is "standard" and style is "decimal".

RangeError

Thrown if locales or options contain invalid values.

In basic use without specifying a locale, a formatted string in the default locale and with default options is returned. This is useful to distinguish between singular and plural forms, e.g. "dog" and "dogs".

const pr = new Intl.PluralRules();

pr.select(0); // 'other' if in US English locale

pr.select(1); // 'one' if in US English locale

pr.select(2); // 'other' if in US English locale

The results can be customized using the options argument, which has one property called type which you can set to ordinal. This is useful to figure out the ordinal indicator, e.g. "1st", "2nd", "3rd", "4th", "42nd", and so forth.

const pr = new Intl.PluralRules("en-US", { type: "ordinal" });

const suffixes = new Map([
  ["one", "st"],
  ["two", "nd"],
  ["few", "rd"],
  ["other", "th"],
]);
const formatOrdinals = (n) => {
  const rule = pr.select(n);
  const suffix = suffixes.get(rule);
  return `${n}${suffix}`;
};

formatOrdinals(0); // '0th'
formatOrdinals(1); // '1st'
formatOrdinals(2); // '2nd'
formatOrdinals(3); // '3rd'
formatOrdinals(4); // '4th'
formatOrdinals(11); // '11th'
formatOrdinals(21); // '21st'
formatOrdinals(42); // '42nd'
formatOrdinals(103); // '103rd'

• Intl.PluralRules
• Intl