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Paraglide JS


#Writing a Framework Library

You can of course write your own framework library if there isn't one for your framework.

Paraglide-Framework-Library integrates with a framework's lifecycle. It does two things:

  1. Calls setLanguageTag() at appropriate times to set the language
  2. Reacts to onSetLanguageTag(), usually by navigating or relading the page.

Additionally, it may provide convenience features such as localised routing.

Many popular frameworks already have libraries available, check out the list of available framework libraries.

If there isn't one for your framework, you can write your own. This example adapts Paraglide to a fictitious full-stack framework.

import {
	type AvailableLanguageTag,
} from "../paraglide/runtime.js"
import { isServer, isClient, request, render } from "@example/framework"
import { detectLanguage } from "./utils.js"

if (isServer) {
	// On the server the language tag needs to be resolved on a per-request basis.
	// Pass a getter function that resolves the language from the correct request

	const detectLanguage = (request: Request): AvailableLanguageTag => {
		//your logic ...
	setLanguageTag(() => detectLanguage(request))

if (isClient) {
	// On the client, the language tag can be resolved from
	// the document's html lang tag.
	setLanguageTag(() => document.documentElement.lang)

	// When the language changes we want to re-render the page in the new language
	// Here we just navigate to the new route

	// Make sure to call `onSetLanguageTag` after `setLanguageTag` to avoid an infinite loop.
	onSetLanguageTag((newLanguageTag) => {
		window.location.pathname = `/${newLanguageTag}${window.location.pathname}`

// Render the app once the setup is done
render((page) => (
	<html lang={request.languageTag}>