jeb

Modern TypeScript rewrite of messageformat/Jed. ESM-only, zero dependencies, drop-in API compatible.

Jed hasn't been touched since 2016. Jeb takes the same gettext API and locale data format and reimplements it in modern TypeScript — no Jison, no AMD/UMD module dance, no eval or new Function.

Credit where it's due: the public API, chain API, locale data format, and overall design are all from Alex Sexton's original Jed. This is a rewrite, not a fork — none of Jed's source is carried over — but it stands entirely on Jed's shoulders.

What changed

• TypeScript source with full type exports
• ESM only ("type": "module")
• Hand-written recursive descent plural-forms parser (no Jison dependency)
• Strict mode: no eval, no new Function, expressions length-capped
• Cached compiled plural functions and sprintf templates
• Hardened count handling: NaN, Infinity, and negative counts are clamped instead of producing garbage plural indices
• textdomain(domain) throws on unknown domains instead of silently switching
• Compiled output targets ES2022, Node ≥ 20

What didn't change

• Same constructor options: { locale_data, domain, debug, missing_key_callback }
• Same locale data JSON format (compatible with po2json output)
• Same gettext API: gettext, ngettext, pgettext, dgettext, dngettext, dpgettext, npgettext, dnpgettext, dcnpgettext, etc.
• Same chain API: translate(key).withContext().ifPlural().onDomain().fetch()
• Same sprintf (static and instance)
• Same context_delimiter (�)
• Same fallback behaviour (missing key returns the key itself)

Install

This package is published to GitHub Packages under the @surgeventures scope.

# .npmrc
@surgeventures:registry=https://npm.pkg.github.com/

npm install @surgeventures/jeb

Migration from Jed

Replace your import:

- import Jed from 'jed';
+ import Jeb from '@surgeventures/jeb';

Everything else stays the same. The constructor, methods, locale data format, and chain API are all compatible.

If you have custom type declarations for Jed (e.g. a jed.d.ts module augmentation), you can delete them — jeb ships its own types.

Usage

import Jeb from '@surgeventures/jeb';

const i18n = new Jeb({
  domain: 'messages',
  locale_data: {
    messages: {
      '': {
        domain: 'messages',
        lang: 'fr',
        plural_forms: 'nplurals=2; plural=(n > 1);',
      },
      Hello: ['Bonjour'],
      '%d item': ['%d article', '%d articles'],
    },
  },
});

i18n.gettext('Hello');                    // 'Bonjour'
i18n.ngettext('%d item', '%d items', 5);  // '%d articles'

Exports

import Jeb, { sprintf, compilePluralForms, extractNPlurals } from '@surgeventures/jeb';
import type { JebOptions, LocaleData, TranslationDomain, DomainMetadata } from '@surgeventures/jeb';

License

MIT. See LICENSE.

The original Jed is © Alex Sexton and contributors, also under MIT. Jeb is an independent reimplementation; no Jed source is included.