# vue: GTPlugin
URL: https://generaltranslation.com/en-US/docs/vue/reference/types/gt-plugin.mdx
---

title: GTPlugin
description: Install Vue translation state and control its locale and catalog cache imperatively. API reference for GTPlugin.

---

[`createGT()`](/docs/vue/reference/functions/create-gt) and [`initializeGTSPA()`](/docs/vue/reference/functions/initialize-gt-spa) return this Vue plugin. Its state and behavior belong to the function that created it.

## Overview [#overview]

```ts
type GTPlugin = {
  getLocale(): string;
  install(app: App): void;
  loadTranslations(locale: string): Promise<TranslationCatalog>;
  setLocale(locale: string): Promise<void>;
};
```

| Method | Description | Return type |
| --- | --- | --- |
| [`getLocale()`](#get-locale) | Return the locale currently owned by the plugin. | `string` |
| [`install(app)`](#install) | Provide the plugin's state to a Vue application. | `void` |
| [`loadTranslations(locale)`](#load-translations) | Preload and cache a locale without changing the active locale. | `Promise<TranslationCatalog>` |
| [`setLocale(locale)`](#set-locale) | Change or persist the active locale according to the plugin's runtime mode. | `Promise<void>` |

## `getLocale()` [#get-locale]

**Type** `() => string` · **Required**

For a [`createGT()`](/docs/vue/reference/functions/create-gt) plugin in the browser, this method reads the current configured locale cookie and falls back to the plugin's explicit or default locale. On the server it returns the instance-local value.

For an [`initializeGTSPA()`](/docs/vue/reference/functions/initialize-gt-spa) plugin, it returns the locale pinned during page initialization. Direct cookie changes do not change the mounted SPA until the next reload and bootstrap.

## `install(app)` [#install]

**Type** `(app: App) => void` · **Required**

Provides translation state to components, formatters, and composables through Vue dependency injection. Calling `app.use(plugin)` calls this method.

Installation starts loading the active locale. A [`createGT()`](/docs/vue/reference/functions/create-gt) plugin can mount immediately with source content and rerender when loading succeeds. An [`initializeGTSPA()`](/docs/vue/reference/functions/initialize-gt-spa) plugin is already preloaded when returned.

Install the exact SPA plugin returned by initialization. Creating and installing a second plugin separates component lookups from module-level [`t()`](/docs/vue/reference/functions/t) lookups. A composable used without any installed plugin throws a diagnostic.

## `loadTranslations()` [#load-translations]

**Type** `(locale: string) => Promise<`[`TranslationCatalog`](/docs/vue/reference/types/translation-catalog)`>` · **Required**

Loads and caches a target catalog without changing the active locale. The default locale returns its existing empty catalog without calling the configured loader.

Successful results remain cached for this plugin, and concurrent calls for the same resolved locale share a promise. On an SPA plugin, locale aliases and supported-locale fallback are applied before loading.

A loader rejection is logged and rethrown. The failure is not cached, so a later call can retry.

## `setLocale()` [#set-locale]

**Type** `(locale: string) => Promise<void>` · **Required**

The transition depends on how the plugin was created:

- **[`createGT()`](/docs/vue/reference/functions/create-gt) plugin:** loads an uncached catalog, then updates the cookie and reactive consumers. A rejected load leaves the existing locale and cookie unchanged. If calls overlap, only the latest request is applied.
- **[`initializeGTSPA()`](/docs/vue/reference/functions/initialize-gt-spa) plugin:** resolves the requested locale, writes the cookie, and reloads the document. It does not load the target catalog or change the pinned locale on the current page before reloading.

[`useSetLocale()`](/docs/vue/reference/composables/use-set-locale) returns this behavior through the installed plugin.

## Example [#example]

```ts
import { createApp } from 'vue';
import { createGT } from 'gt-vue';
import App from './App.vue';

const gt = createGT({ defaultLocale: 'en', loadTranslations });

await gt.loadTranslations('fr');
createApp(App).use(gt).mount('#app');

await gt.setLocale('fr');
console.log(gt.getLocale()); // "fr"
```