Localize URL

SvelteKit library that handles URL localization and routing.

Note This package is WIP. It works but the future updates may introduce breaking changes to simplify setup or introduce features.

Features

Supports 3 URL structure types:
- Locale prefix except for the base locale (default) - /about, /ru/o-nas;
- Prefix for every locale - /en/about, /ru/o-nas;
- Separate domains for locales - example.com/about, example.ru/o-nas.
Validates current URL:
- Redirects /ru/about-us to the corrected /ru/o-nas;
- Supports partially localized pages - throws 404 if a page isn’t available for the requested locale.
Helps to build localized URLs;
Builds alternate URLs for the <link rel="alternate" tags and for a language switcher;
Supports dynamic params that depend on the server (such as localized post slugs).

Interactive Live Demo

https://sveltekit-localize-url.vercel.app/

Compatibility

This library was initially created to be used with the typesafe-i18n library, but should work fine with any i18n library (or even without one).

Installation

npm install sveltekit-localize-url

Usage

Please take a look the example for the full setup.

How does it work?

Let's imagine that:

Your default/base locale is en and enabled locales are en, ru and it;
You have the following structure: /[[lang=lang]]/[l_about=l_about];
Your l_about param is registered like this:

// src/params/l_about.ts
import { localizeParam, matchParam } from 'sveltekit-localize-url';

const localizedParam = localizeParam(1, 'l_about', {
	en: 'about-us',
	ru: 'o-nas'
	// there is NO version in Italian
});
export const match: ParamMatcher = (param) => matchParam(param, localizedParam);

When SvelteKit will match params, it will decide that all of following paths are valid:

/about-us
/en/about-us
/ru/about-us
/it/about-us
/o-nas
/en/o-nas
/ru/o-nas
/it/o-nas

However the validateUrlLocale() function that is called in the src/routes/[[lang=lang]]/+layout.ts will take care of that by taking registered params and using them to construct a correct path for the current locale.

If the paths match, proceed;
If the paths don't match, redirect to a corrected URL;
If it can't construct a path for the current locale, throw 404.

So in the end we'll get the following:

/about-us - Correct;
/ru/o-nas - Correct;
/o-nas, /en/about-us, /en/o-nas - Redirect to /about-us;
/ru/about-us - Redirect to /ru/o-nas;
/it/about-us, /it/o-nas - 404 Not Found.