beacon-web/docs/translations.md

Translating Beacon

The header language picker starts in English and saves the selected language in this browser; an unset or empty string in a catalog falls back to English.

Add a language

1. Copy src/i18n/locales/en.json to a language-tag filename such as de.json.
2. Set name to its native name, such as Deutsch. Translate string values under translation; keep their keys and interpolation placeholders intact.
3. Build and test. Vite discovers every JSON catalog in that directory, and its native name appears in the language picker automatically. No central language list, plugin or translation server is needed.

Missing or empty translations fall back to English. Catalogs are bundled with the application, so a new language requires a web build/deployment. Keep English as the complete source catalog. Every selectable language must have a native name and at least one translated string. Use plain text, not HTML, in translations.

Add translated UI text

import { useTranslation } from "react-i18next";

function LoadingMessage() {
  const { t } = useTranslation();
  return <span>{t("common.loading")}</span>;
}

Add the English key/value and translate it in other catalogs where possible.

• Use t("region.count", { count }) with i18next's language-specific plural suffixes (_one, _other, and _many where applicable).
• Preserve placeholders such as {{seconds}}; translate the whole phrase rather than joining words.
• Never translate tab IDs, URL parameters, IATA codes, query keys, or packet contents.
• Chart helpers receive t explicitly, and their memoized options must depend on t so labels redraw when the language changes.
• Sortable tables need a stable Column.id (e.g. defaultSort={{ id: "drift", direction: "desc" }}) so the visible header can change language without losing sorting or focus.
• Shared Timestamp uses the whole timestamp.ago phrase with {{duration}}, so a translation can reorder duration and phrase (e.g. French's "il y a").

Verify

Run npm run build, npm run lint and npm test. Tests use the real i18next catalogs and reset to English after each test.