@postalsys/gettext

@postalsys/gettext is a JavaScript implementation of (a large subset of) gettext, a localization framework originally written in C.

If you just want to parse or compile mo/po files, for use with this library or elsewhere, check out gettext-parser.

Features
- Differences from GNU gettext
Installation
Usage
- Error events
- Recipes
API
License
See also

Features

Supports domains, contexts and plurals
Supports .json, .mo and .po files with the help of gettext-parser
Ships with plural forms for 136 languages
Change locale or domain on the fly
Useful error messages enabled by a debug option
Emits events for internal errors, such as missing translations

Differences from GNU gettext

There are two main differences between @postalsys/gettext and GNU's gettext:

There are no categories. GNU gettext features categories such as LC_MESSAGES, LC_NUMERIC and LC_MONETARY, but since there already is a plethora of great JavaScript libraries to deal with numbers, currencies, dates etc, @postalsys/gettext is simply targeted towards strings/phrases. You could say it just assumes the LC_MESSAGES category at all times.
You have to read translation files from the file system yourself. GNU gettext is a C library that reads files from the file system. This is done using bindtextdomain(domain, localesDirPath) and setlocale(category, locale), where these four parameters combined are used to read the appropriate translations file.

However, since @postalsys/gettext needs to work both on the server in web browsers (which usually is referred to as it being universal or isomorphic JavaScript), it is up to the developer to read translation files from disk or somehow provide it with translations as pure JavaScript objects using addTranslations(locale, domain, translations).

bindtextdomain will be provided as an optional feature in a future release.

Installation

npm install --save @postalsys/gettext

Usage

const Gettext = require('@postalsys/gettext');
const swedishTranslations = require('./translations/sv-SE.json');

const gt = new Gettext();
gt.addTranslations('sv-SE', 'messages', swedishTranslations);
gt.setLocale('sv-SE');

gt.gettext('The world is a funny place');
// -> "Världen är en underlig plats"

Error events

// Add translations etc...

gt.on('error', error => console.log('oh nose', error));
gt.gettext('An unrecognized message');
// -> 'oh nose', 'An unrecognized message'

Recipes

Load and add translations from .mo or .po files

@postalsys/gettext expects all translations to be in the format specified by gettext-parser. Therefor, you should use that to parse .mo or .po files.

Here is an example where we read a bunch of translation files from disk and add them to our Gettext instance:

const fs = require('fs');
const path = require('path');
const Gettext = require('@postalsys/gettext');
const { po } = require('gettext-parser');

// In this example, our translations are found at
// path/to/locales/LOCALE/DOMAIN.po
const translationsDir = 'path/to/locales';
const locales = ['en', 'fi-FI', 'sv-SE'];
const domain = 'messages';

const gt = new Gettext();

locales.forEach(locale => {
    const fileName = `${domain}.po`;
    const translationsFilePath = path.join(translationsDir, locale, fileName);
    const translationsContent = fs.readFileSync(translationsFilePath);

    const parsedTranslations = po.parse(translationsContent);
    gt.addTranslations(locale, domain, parsedTranslations);
});

API

Gettext

Gettext
- new Gettext([options])
- .on(eventName, callback)
- .off(eventName, callback)
- .addTranslations(locale, domain, translations)
- .setLocale(locale)
- .setTextDomain(domain)
- .gettext(msgid) ⇒ String
- .dgettext(domain, msgid) ⇒ String
- .ngettext(msgid, msgidPlural, count) ⇒ String
- .dngettext(domain, msgid, msgidPlural, count) ⇒ String
- .pgettext(msgctxt, msgid) ⇒ String
- .dpgettext(domain, msgctxt, msgid) ⇒ String
- .npgettext(msgctxt, msgid, msgidPlural, count) ⇒ String
- .dnpgettext(domain, msgctxt, msgid, msgidPlural, count) ⇒ String
- .textdomain()
- .setlocale()

new Gettext([options])

Creates and returns a new Gettext instance.

Returns: Object - A Gettext instance Params

[options]: Object - A set of options
- .sourceLocale: String - The locale that the source code and its texts are written in. Translations for this locale is not necessary.
- .debug: Boolean - Whether to output debug info into the console.

gettext.on(eventName, callback)

Adds an event listener.

Params

eventName: String - An event name
callback: function - An event handler function

gettext.off(eventName, callback)

Removes an event listener.

Params

eventName: String - An event name
callback: function - A previously registered event handler function

gettext.addTranslations(locale, domain, translations)

Stores a set of translations in the set of gettext catalogs.

Params

locale: String - A locale string
domain: String - A domain name
translations: Object - An object of gettext-parser JSON shape

Example

gt.addTranslations('sv-SE', 'messages', translationsObject);

gettext.setLocale(locale)

Sets the locale to get translated messages for.

Params

locale: String - A locale

Example

gt.setLocale('sv-SE');

gettext.setTextDomain(domain)

Sets the default gettext domain.

Params

domain: String - A gettext domain name

Example

gt.setTextDomain('domainname');