i18n

Isomorphic translation engine. Mimics Rails' i18n interface.

Usage

const I18n = require('@fiverr/i18n');
const translations = require('./translations.json');

const i18n = new I18n({translations});

Option	Type	Description
translations	Object	Representation of translation structure Must be JSON compliant otherwise will be treated like an empty object
missing	Function	Call this function when a key is missing. Function accepts arguments: key, scope, translations_object
empty	Function	Call this function when a value is empty. Function accepts arguments: key, value, scope, translations_object
$scope	String	Omittable prefix. see Scope The base is translations key root

const i18n = new I18n({
    translations: {...},
    missing: key => logMissingKeyEvent({key: `missing_translation.${key.replace(/\W/g, '_')}`}),
    empty: key => logEmptyValueEvent({key: `empty_translation.${key.replace(/\W/g, '_')}`}),
    $scope: 'my_app.en'
});

Translate

i18n.t('my.key'); // I'm a sentence

Find alternatives

i18n.t(['my.missing.key', 'my.key']); // I'm a sentence

Handle missing

By default, missing keys or empty values return the last part of the key

i18n.t('this.is.a.missing_key'); // missing key

But returning a truthy value from 'missing' and 'empty' callbacks will allow a custom fallback

const i18n = new I18n({
    translations: {...},
    empty: (key, value, scope) => {
        if (scope.startsWith('en-US')) {
            return; // default fallback
        }
        return i18n.t(key, { $scope: 'en-US' }); // Try English
    },
    $scope: 'en-US'
});

Add more translations after instantiation

i18n.add({yet: {another: {key: 'I\'m here, too!'}}});
Use:
i18n.translate('yet.another.key'); // I'm here, too!
Or:
i18n.t('yet.another.key'); // I'm here, too!

Features

Interpolate with data

const i18n = new I18n({
    translations: {
        my: { string: 'a dynamic %{thing} in a static string' }
    }
});
i18n.t('my.string', {thing: 'value'}); // a dynamic value in a static string

One/other

const i18n = new I18n({
    translations: {
        it_will_take_me_days: {
            one: 'It\'ll take me one day',
            other: 'It\'ll take me %{count} days'
        }
    }
});
i18n.t('it_will_take_me_days', {count: 1}); // It'll take me one day
i18n.t('it_will_take_me_days', {count: 3}); // It'll take me 3 days
i18n.t('it_will_take_me_days', {count: 'a lot of'}); // It'll take me a lot of days

Instance with a scope

Priority:

1. Found result with passed in scope (when applicable)
2. Found result with instance set scope (when applicable)
3. Found result w/o scope

// Global scope setup
const i18n = new I18n({
    translations: {
        key: 'Top',
        child: {
            key: 'Child'
        },
        something: {
            key: 'Something'
        }
    }
});
const child = i18n.spawn('child');

i18n.t('key'); // Top
child.t('key'); // Child
child.t('key', { $scope: 'something' }); // Something

Scoped child instance

This is a good option for shorthand in enclosed parts of the application.

The translation store is shared so the parent can find the keys if it prefixes the namespace, and the child doesn't need to.

The child can also find "global" translations (ones that are outside it's namespace)

const usersI18n = i18n.spawn('users.get');

// Add translations under the scope
usersI18n.add({introduction: 'Hi, my name is %{username}'});

// Use translations
usersI18n.t('introduction', {username: 'Martin'}); // Hi, my name is Martin
i18n.t('users.get.introduction', {username: 'Martin'}); // Hi, my name is Martin

Instance

Exposes an empty instance of i18n

const i18n = require('@fiverr/i18n/instance');

i18n.add({...});

Made especially for use as a webpack external

externals: {
  '@fiverr/i18n/instance': 'i18n'
}

Name can alternate:

import phraser from '@fiverr/i18n/instance';

externals: {
  '@fiverr/i18n/instance': 'phraser'
}

Singleton (i18n)

Make sure you only have one instance of I18n in your global scope

const i18n = I18n.singleton;

// Optional:
i18n.$scope = 'my.scope';
i18n.onmiss((key, scope) => console.error(`Missing key "${key}" ${scope ? `In scope: "${scope}"`}`));
i18n.onempty((key, value, scope) => console.warn(`Empty value "${value}" for key "${key}" ${scope ? `In scope: "${scope}"`}`));
i18n.add({...});

Shortcut:

const i18n = require('@fiverr/i18n/singleton');

Or simply

require('@fiverr/i18n/singleton');

// i18n is defined globally

Helper functions

Check if a key is available

has

i18n.has('key');
i18n.has(['key', 'other_key']);
i18n.has('namespace.key');
i18n.has('key', { $scope: 'namespace' });