Pluralization

Leaves can be plural objects keyed by CLDR category (zero | one | two | few | many | other). Ilingo selects the matching form via Intl.PluralRules keyed by the resolved locale.

TS/JS: definePlural

Author plurals with the definePlural helper. Its argument type is PluralForms, so you get autocomplete for the CLDR categories and a compile error on a missing other / non-CLDR key:

import { defineNamespace, defineTranslations, definePlural } from 'ilingo';

defineNamespace('cart', [
    defineTranslations({
        items: definePlural({
            one: '{{count}} item',
            other: '{{count}} items',
        }),
    }),
]);

definePlural returns a plural node ({ type: 'plural', data: forms }). A plain { one, other } object passed to defineTranslations is not a plural — it's a key-nested map, so siblings called one, other, etc. are reachable via dotted access. Only a node produced by definePlural (or the literal { "type": "plural", ... } form in JSON) is interpreted as a plural.

JSON

JSON cannot call functions, so a plural is spelled as a literal plural node inside the file's translations node:

{
    "type": "translations",
    "data": {
        "items": {
            "type": "plural",
            "data": { "one": "{{count}} item", "other": "{{count}} items" }
        }
    }
}

Both forms produce identical runtime data — Intl.PluralRules doesn't care which authoring path produced the leaf.

Selection rules

await ilingo.get({ namespace: 'cart', key: 'items', count: 0 }); // 'other' (en has no 'zero')
await ilingo.get({ namespace: 'cart', key: 'items', count: 1 }); // 'one'
await ilingo.get({ namespace: 'cart', key: 'items', count: 5 }); // 'other'

• If the selected category is absent, other is used.
• The locale used by Intl.PluralRules is the resolved locale (the one that actually yielded the leaf), not the requested one. Useful when en-US → en falls back and you want the English plural rules to apply.

Caching

Intl.PluralRules instances are cached per locale on the Ilingo instance. Repeated calls do not reallocate.

Round-tripping

Plural leaves go through store.set() cleanly — StoreSetContext.value accepts a string or a plural node (definePlural(...) / { type: 'plural', data }), not the unwrapped PluralForms, so the store recognises and unwraps it on read. FSStore.set persists it as JSON unchanged.