🚀 Feature Proposal

There has to be an option:

1. either to pass custom language codes with their pluralization rules, i.e.:

i18next.init({
  // ...
  pluralRules: [
    {
      lngs: ['art-x-interslv'],
      nr: [1,2,5],
      fc(n) {return Number(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);},
    },
  ],
});

2. or to parse CLCR convention of art-x-???????? (where ???????? is the language name) in your LanguageUtils.js (getLanguagePartFromCode) and allow adding significant enough constructed languages. For example:

art-x-neolatin → neolatin
art-x-interslv → interslv

Motivation

I want to contribute Interslavic translation to Allure Reporter, and the maintainers are okay about this, but...

The problem is that their project is using i18next, where I cannot configure pluralization rules for Interslavic language:

For reasons of clarity, however, it is recommended to use the nominative singular after 1, the nominative plural after 2-4 and the genitive plural after 5 and more: 1 dom, 2 domy, 3 domy, 4 domy, 5 domov. ¹²

Although new Intl.PluralRules(...) may never work correctly for some minority languages, I hope that this issue can be mitigated on the compatibility layer level (v1-v3) at the very least.

Example

While the basic functionality of i18next works, this feature would enable translating plurals in unrecognized languages, which is essential to build software supporting these languages and contributing to their development: