Translation

The UI Kit uses i18next and react-i18next for internationalization. Translation resources are passed in at the application level via TranslationProvider.

Translation files

The package ships English only, one file per namespace:

locales/
└── en/
    ├── Common.json
    ├── Payments.json
    └── Settings.json

Every other language comes from the host application: it loads its own resources and hands them to TranslationProvider, which is why the same component reads Russian in the portal and English in Storybook without the package carrying either.

Each JSON file is a flat key-value map. Keys use PascalCase:

{
  "SaveButton": "Save",
  "CancelButton": "Cancel",
  "DeleteMessage": "Are you sure you want to delete {{name}}?"
}

Setting up TranslationProvider

Wrap your application with TranslationProvider and pass translation resources as a nested Map:

import { TranslationProvider } from "@onlyoffice/apps-ui-kit/providers/translation";
import type { TTranslations } from "@onlyoffice/apps-ui-kit/providers/translation";

import enCommon from "@onlyoffice/apps-ui-kit/locales/en/Common.json";
import frCommon from "./locales/fr/Common.json"; // your own resources: the package ships English only

const translations: TTranslations = new Map([
  ["en", new Map([["Common", enCommon]])],
  ["fr", new Map([["Common", frCommon]])],
]);

<TranslationProvider translations={translations} locale="en">
  <App />
</TranslationProvider>

Provider props

• translations (TTranslations) — nested Map: language → namespace → key-value records
• locale (string) — current language code (highest priority)
• user ({ cultureName?: string }) — optional; cultureName used as fallback locale
• settings ({ culture?: string; timezone?: string }) — optional; culture used as second fallback

Language resolution order: locale → user.cultureName → settings.culture → "en"

Using translations in components

Use the useTranslation hook from react-i18next:

import { useTranslation } from "react-i18next";

function MyComponent() {
  const { t } = useTranslation(["Common"]);

  return <button>{t("Common:SaveButton")}</button>;
}

Multiple namespaces

const { t } = useTranslation(["Files", "Common"]);

t("Files:DeleteMessage")   // from Files namespace
t("Common:CancelButton")   // from Common namespace

Interpolation

Use double curly braces for variable substitution:

// Common.json
// { "Greeting": "Hello, {{name}}!" }

t("Common:Greeting", { name: "Alice" })
// → "Hello, Alice!"

JSX inside translations (Trans component)

Use the Trans component when you need to embed React elements inside translated strings:

import { Trans, useTranslation } from "react-i18next";

// Common.json
// { "Info": "Contact <1>support</1> for help." }

function HelpText() {
  const { t } = useTranslation(["Common"]);

  return (
    <Trans
      t={t}
      ns="Common"
      i18nKey="Info"
      components={{ 1: <a href="/support" /> }}
    />
  );
  // → Contact <a href="/support">support</a> for help.
}

getCommonTranslation

For cases where you need a translation outside of React (event handlers, utility functions, MobX stores), use getCommonTranslation from @onlyoffice/apps-ui-kit/utils/i18n. It reads from the Common namespace only.

import { getCommonTranslation } from "@onlyoffice/apps-ui-kit/utils/i18n";

// Simple key lookup
const label = getCommonTranslation("SaveButton");

// With interpolation
const message = getCommonTranslation("DeleteMessage", { name: "Report.docx" });

How it works

1. Tries window.i18n.t() first (set by TranslationProvider).
2. Falls back to manual lookup from window.i18n.loaded using the language from the asc_language cookie.
3. Logs an error if the key is not found and returns an empty string.

Many internal components use getCommonTranslation to provide default labels (buttons, empty screens, error pages) so that they work without an explicit t prop. If TranslationProvider is mounted, translations resolve automatically.

getTranslationReady

Use getTranslationReady to check whether translations have been loaded before rendering:

import { getTranslationReady } from "@onlyoffice/apps-ui-kit/utils/i18n";

if (getTranslationReady()) {
  // Safe to call getCommonTranslation
}

Adding a new language

1. Create a new folder under locales/ with the language code (e.g. locales/ja-JP/).
2. Copy the English JSON files and translate the values.
3. Add the new language to the translations Map passed to TranslationProvider.

Adding a new translation key

1. Add the key to the English JSON file first (e.g. locales/en/Common.json).
2. Add translations for other languages in their respective files.
3. Use the key in your component via t("Common:YourNewKey").