basic-l10n

basic localization of strings (391 bytes gzip, no dependencies), including pluralization and reordering of substitutions with template literals.

in the non-minified version (basic-l10n/dist/index.js), unknown template literals generate a warning when a logger is provided, unless process.env.NODE_ENV === "production". in all cases, unknown template literals are returned as they would from the default template function, without localization.

Example

see this example in this directory.
run this example in your browser.

import createL10n from 'basic-l10n/dist/index.js' // dev version with debug warnings
import log from './console'
const log = logger()
const debug = logger('(debug)')

const localizations = {
  en: {
    'welcome': 'welcome', // default string localization
    'date: %s/%s/%s': 'date: %0/%1/%2',
    'you have %s new messages.': [ // pluralization
      'you have no new messages.', // 0
      'you have one new message.', // 1
      'you have %0 new messages.' // 2 and more
      // not limited to 3 entries, could be any number
    ]
  },
  fr: {
    'welcome': 'bienvenue',
    'date: %s/%s/%s': 'date: %1/%0/%2', // reorder substitutions
    'you have %s new messages.': [
      'vous n\'avez pas de nouveaux messages.',
      'vous avez un nouveau message.',
      'vous avez %0 nouveaux messages.'
    ]
  }
}

const l10n = createL10n(localizations, { debug })

for (const lang of ['en', 'fr']) {
  l10n.locale = lang
  log(l10n('welcome')) // default string localization
  log(l10n`date: ${1}/${7}/${1982}`) // reordering with template strings
  for (const count of [0, 1, 5]) {
    log(l10n`you have ${count} new messages.`) // pluralization with template strings
  }
}
log(l10n`unknown keys generate a warning`) // except in production

output to console:

welcome
date: 1/7/1982
you have no new messages.
you have one new message.
you have 5 new messages.
bienvenue
date: 7/1/1982
vous n'avez pas de nouveaux messages.
vous avez un nouveau message.
vous avez 5 nouveaux messages.
(debug) WARNING: undefined localization for locale "fr" and key "unknown template literals generate a warning"
unknown template literals generate a warning

API

export default function createL10n(
  localizations?: Localizations,
  opts?: Partial<L10nOptions>
): L10nTag

export interface L10nTag {
  (key: string): string
  (strings: TemplateStringsArray, ...substitutions: any[]): string
  localizations: Localizations
  locale: string
}
export interface Localizations {
  [locale: string]: {
    [key: string]: string[] | string
  }
}
export interface L10nOptions {
  locale: string
  debug: (...args: any[]) => void
}

for a detailed specification of this API, in particular for handling of corner cases, run the unit tests in your browser.

TypeScript

although this library is written in TypeScript, it may also be imported into plain JavaScript code: modern code editors will still benefit from the available type definition, e.g. for helpful code completion.

License

Copyright 2018 Stéphane M. Catala

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and Limitations under the License.