html-lang-primary-subtags

TypeScript union type for primary language subtags (ISO-639 / IANA) compatible with the HTML lang="" attribute.

This package provides a strictly typed union of all registered primary language subtags, without regions, scripts, variants, or extensions.

Useful for:

- typing HTML lang attribute safely
- typing multilingual function params
- autocomplete of valid language codes
- avoiding invalid language identifiers at compile time

---

Install

``bash
npm install html-lang-primary-subtags
`

Use

`ts
import type { PrimaryLanguageSubtag } from "html-lang-primary-subtags";

const lang: PrimaryLanguageSubtag = "en"; // ok
// const invalid: PrimaryLanguageSubtag = "en-US"; // compile-time error
`

PrimaryLanguageSubtag is a union of all registered primary language subtags (ISO-639) suitable for the HTML lang attribute without region/script/variant extensions.

Types

- PrimaryLanguageSubtag – primary language subtags (ISO-639-1)
- RegionSubtag – uppercase region codes (ISO-3166-1 alpha-2)
- Bcp47Locale – ${PrimaryLanguageSubtag}-${RegionSubtag} for HTML lang (BCP-47)
- OgLocale – ${PrimaryLanguageSubtag}_${RegionSubtag} for Open Graph tags

$3

`ts
import type {
PrimaryLanguageSubtag,
RegionSubtag,
Bcp47Locale,
OgLocale,
} from "html-lang-primary-subtags";

const lang: PrimaryLanguageSubtag = "en";
const region: RegionSubtag = "US";
const bcp47: Bcp47Locale = "en-US";
const ogLocale: OgLocale = "en_US";
`

Changelog

See CHANGELOG.md` for release notes.