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Dynamic loading of message catalogs

I18nProvider doesn't assume anything about your app and it's the developer responsibility to load messages based on active language.

Here's an example of a basic setup with a dynamic load of catalogs.

Final I18n loader helper

Here's the full source of i18n.ts logic:

import { i18n } from "@lingui/core";

export const locales = {
en: "English",
cs: "Česky",
export const defaultLocale = "en";

* We do a dynamic import of just the catalog that we need
* @param locale any locale string
export async function dynamicActivate(locale: string) {
const { messages } = await import(`./locales/${locale}/messages`);
i18n.load(locale, messages);

How should I use the dynamicActivate in our application?

import React, { useEffect } from "react";
import App from "./App";

import { I18nProvider } from "@lingui/react";
import { i18n } from "@lingui/core";
import { defaultLocale, dynamicActivate } from "./i18n";

const I18nApp = () => {
useEffect(() => {
// With this method we dynamically load the catalogs
}, []);

return (
<I18nProvider i18n={i18n}>
<App />


Looking at the content of build dir, we see one chunk per language:


When page is loaded initially, only main bundle and bundle for the first language are loaded:

Requests during the first render

After changing language in UI, the second language bundle is loaded:

Requests during the second render

And that's it! 🎉