svelte-lang Svelte Themes

Svelte Lang

svelte-lang is an i18n library for Svelte that simplifies multilingual support. It offers a straightforward API for managing translations, supports parameterized strings, autocompletion, and integrates with Svelte stores for reactive language handling. Features include automatic language detection, making it easy to build global applications.

svelte-lang

An internationalization (i18n) library for Svelte applications, designed to make multilingual support simple and efficient.

Features

  • Simple Setup: Easily integrate with Svelte applications.
  • Template Literal Translations: Use template literals for translations, keeping code clean and readable.
  • Parameterized Translations: Support dynamic parameters within translation strings.
  • Language Persistence: Optionally persist the selected language in localstorage.
  • Automatic Language Detection: Detect user language preferences from the browser.
  • Inline Parameters: Support inline parameters in translation keys.
  • Svelte Stores Integration: Uses Svelte stores for reactive language and translation handling.

Installation

npm install svelte-lang

How to Use

Setup Translations

Create translation files for each language in your project.

Example: English Translations (en.ts)

// src/lib/i18n/translations/en.ts
import { t, p } from 'svelte-lang';

export const en = {
  app: t`svelte-lang`,
  'Something went wrong': t`Something went wrong`,
  'Welcome $name': t`Welcome ${p('name')}`
} as const;

Example: German Translations (de.ts)

// src/lib/i18n/translations/de.ts
import { t, p } from 'svelte-lang';

export const de = {
  app: t`svelte-lang`,
  'Something went wrong': t`Etwas ist schief gelaufen`,
  'Welcome $name': t`Willkommen ${p('name')}`
} as const;

Initialize i18n

Set up the i18n configuration in your project.

// src/lib/i18n/index.ts
import { setupI18n } from 'svelte-lang';
import { en } from './translations/en';
import { de } from './translations/de';

export const translations = {
  en,
  de
} as const;

export const { t, language, supportedLanguages, tUnsafe, initLanguage } = setupI18n(
  translations,
  'en', // Default language
  { languagePersisted: true } // Persist language selection in localstorage
);

Update app.d.ts

Ensure that the language property is available in the App.Locals interface.

// src/app.d.ts
declare global {
  namespace App {
    interface Locals {
      language: string;
    }
  }
}

export {};

Implement Language Detection Hook

Use a server hook to detect and set the user's preferred language.

// src/hooks.server.ts
import { translations } from '$lib/i18n';
import { i18nHook } from 'svelte-lang';

export const handle = i18nHook(translations, 'en');

Add to existing Hook

// src/hooks.server.ts
import { translations } from '$lib/i18n';
import { i18nHook } from 'svelte-lang';
import { sequence } from '@sveltejs/kit/hooks';
import { anotherHook } from './anotherHook';

// Combine multiple hooks
export const handle = sequence(
  i18nHook(translations, 'en'),
  anotherHook
  // Add more hooks as needed
);

Initialize Language in Layout

Set the initial language in your root layout.

<!-- src/routes/+layout.svelte -->
<script lang="ts">
  import { initLanguage } from '$lib/i18n';
  import type { LayoutData } from './$types';

  export let data: LayoutData;

  initLanguage(data.language);
</script>

<slot />
// src/routes/+layout.server.ts
import type { LayoutServerLoad } from './$types';

export const load: LayoutServerLoad = async ({ locals }) => {
  return { language: locals.language };
};

Use Translations in Components

Use the t function to retrieve translations in your Svelte components.

<!-- src/routes/+page.svelte -->
<script lang="ts">
  import { language, supportedLanguages, t, tUnsafe } from '$lib/i18n';

  let name = 'John';
  let dynamicKey = 'app';
  let inlineParamsKey = 'Welcome $name({"name": "John"})';
</script>

<main>
  <h1>{$t('app')}</h1>

  <div>
    <label for="language">Select Language:</label>
    <select id="language" bind:value={$language}>
      {#each supportedLanguages as lang}
        <option value={lang}>{lang}</option>
      {/each}
    </select>
  </div>

  <div>
    <label for="name">Name:</label>
    <input id="name" type="text" bind:value={name} />
    <p>{$t('Welcome $name', { name })}</p>
  </div>

  <div>
    <h2>Dynamic Key Translation:</h2>
    <label for="dynamic-key">Key:</label>
    <input id="dynamic-key" type="text" bind:value={dynamicKey} />
    <p>{$tUnsafe(dynamicKey)}</p>
  </div>

  <div>
    <h2>Inline Parameters:</h2>
    <label for="inline-params-key">Key:</label>
    <input id="inline-params-key" type="text" bind:value={inlineParamsKey} />
    <p>{$tUnsafe(inlineParamsKey)}</p>
  </div>
</main>

Accessing Translations with Parameters

To include dynamic parameters in your translations, use the p function when defining translations and pass the parameters when retrieving them.

Defining a Translation with Parameters

// In your translation file
'Welcome $name': t`Welcome ${p('name')}`,

Retrieving a Translation with Parameters

<p>{$t('Welcome $name', { name: 'Alice' })}</p>

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any bugs or feature requests.

License

This project is licensed under the MIT License.

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