This tutorial will walk you through using Lingui's internationalization (i18n) features in a vanilla JavaScript application. We'll cover the essentials of the @lingui/core package, which handles all translation and message catalog management.

:::tip Example If you're looking for a working solution, check out the Vanilla JS example. This example application shows a complete setup using Lingui and vanilla JavaScript. :::

1. Follow the Installation and Setup page for initial setup.
2. Install the @lingui/core package, which is responsible for translation and message catalog handling.

First, we need to set up the i18n singleton, which is pretty simple:

import { i18n } from "@lingui/core";
import { messages } from "path-to-locale/en/messages.js";

i18n.load("en", messages);
i18n.activate("en");

The messages.js is generated by the Lingui CLI and contains compiled message catalogs.

:::tip Alternatively, you can load catalogs dynamically using the @lingui/loader or @lingui/vite-plugin without the need to import compiled messages manually. :::

To localize your application, you need to wrap your localizable texts in Macros. Lingui provides a set of Core Macros that transform tagged template literals and can be used in any JavaScript context.

Let's wrap our text in the t macro:

import { t } from "@lingui/core/macro";

t`Hello World!`;
// becomes "Salut le monde!"

const name = "Fred";
t`My name is ${name}`;
// becomes "Je m'appelle Fred"

Plurals and selections are possible using plural and select macros:

import { plural } from "@lingui/core/macro";

const count = 42;

plural(count, {
  one: "# book",
  other: "# books",
});
// becomes "42 livres"

It's also possible to nest message formats. Each message format method in i18n has a standalone companion, which only returns message without performing the translation:

import { t, select, plural } from "@lingui/core/macro";

select(gender, {
  offset: 1,
  female: plural(numOfGuests, {
    offset: 1,
    0: t`${host} does not give a party.`,
    1: t`${host} invites ${guest} to her party.`,
    2: t`${host} invites ${guest} and one other person to her party.`,
    other: t`${host} invites ${guest} and # other people to her party.`
  }),
  male: plural(value, {...}),
  other: plural(value, {...}),
});

:::caution All Core Macros cannot be used at the module level. They must be used within a component or function. See the Macros documentation for more information. :::

• Message Extraction Guide
• Pluralization Guide
• Dynamic Loading of Message Catalogs
• Lingui CLI Reference