Translates Unicode CLDR pluralization rules to executable JavaScript

Usage no npm install needed!

<script type="module">
  import makePluralCompiler from '';



make-plural-compiler translates Unicode CLDR pluralization rules to JavaScript functions. A precompiled build of its output is published separately as the make-plural package.

Installation & Usage

npm install make-plural-compiler
import { Compiler, compileRange } from 'make-plural-compiler'

Compiler.load(cldr, ...)

Loads CLDR rules from one or more cldr variables, each of which must be an object formatted like this.

No plural data is included by default, so you'll need to call this at least once, or otherwise fill the Compiler.rules object.

The default CLDR rules are available from the cldr-core package, and may be loaded as seen in the examples below.

new Compiler(lc, { cardinals, ordinals })

Creates a new compiler for the given locale lc. If no direct match for lc is found, it is compared case-insensitively to known locales.

The optional second parameter may contain the following boolean members:

  • cardinals — if true, rules for cardinal values (1 day, 2 days, etc.) are included
  • ordinals — if true, rules for ordinal values (1st, 2nd, etc.) are included

If the second parameter is undefined, the values are taken from Compiler.cardinals (default true) and Compiler.ordinals (default false).


Returns a function that takes an argument n and returns its plural category for the given locale. The function has an overloaded toString(name) method that may be used to generate a clean string representation of the function, with an optional name name.

If the compiler's cardinals and ordinals options are both true, the returned function takes a second parameter ord. Then, if ord is true, the function will return the ordinal rather than cardinal category applicable to n in locale lc.


Available after compile() has been called, test() verifies that all of the sample values included in the rules' samples are correctly categorised by teh compiled function. Either throws an error or returns undefined on success.

import plurals from 'cldr-core/supplemental/plurals.json'
import ordinals from 'cldr-core/supplemental/ordinals.json'
import { Compiler } from 'make-plural-compiler'

Compiler.load(plurals, ordinals)
// { [Function: Compiler]
//   cardinals: true,
//   ordinals: false,
//   foldWidth: 78,
//   rules:
//    { cardinal:
//       { af: [Object],
//         ak: [Object],
//         am: [Object],
//         [snip many lines...]
//         yue: [Object],
//         zh: [Object],
//         zu: [Object] },
//      ordinal:
//       { af: [Object],
//         am: [Object],
//         ar: [Object],
//         [snip slightly fewer lines...]
//         yue: [Object],
//         zh: [Object],
//         zu: [Object] } } }

var skc = new Compiler('sk') // Note: not including ordinals by default
// Compiler {
//   lc: 'sk',
//   categories: { cardinal: [], ordinal: [] },
//   parser: Parser {},
//   tests: Tests { lc: 'sk', ordinal: {}, cardinal: {} },
//   types: { cardinals: true, ordinals: false } }

var sk = skc.compile()
// [Function: anonymous] { toString: [Function (anonymous)] }

// undefined

// 'one'

// 'few'

// 'many'

// 'other'

// (n) => {
//   const s = String(n).split('.'), i = s[0], v0 = !s[1];
//   return n == 1 && v0 ? 'one'
//     : (i >= 2 && i <= 4) && v0 ? 'few'
//     : !v0 ? 'many'
//     : 'other';
// }


Compiles Unicode CLDR plural range data into a corresponding JavaScript function. data should be an object with keys matching the regular expression ^pluralRange-start-(\w+)-end-(\w+)$, and valid CLDR category identifiers as values.

Returns a function, which when given a start and an end category as arguments, determines the plural category of the entire range.


This library has no explicit dependencies, but it will require CLDR plural rule data to be useful; the LDML Language Plural Rules as used in CLDR release 24 and later are supported.

The canonical source for the data is cldr-core (as shown above), but the compiler may also be used e.g. with cldr-data:

const cldr = require('cldr-data')
const { Compiler } = require('make-plural-compiler')

Compiler.load(cldr('supplemental/plurals'), cldr('supplemental/ordinals'))
const enc = new Compiler('en')
const en = enc.compile()
en(3, true)
// 'few'