An implementation of routes localization for Angular


182481.0.0-rc.3.14 years ago4 years agoMinified + gzip package size for @wishtack/localize-router in KB



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An implementation of routes localization for Angular.

Based on and extension of ngx-translate. Demo project can be found here or under sub folder demo/cli.

This documentation is for version 1.x.x which requires Angular 4+. If you are migrating from the older version follow migration guide to upgrade to latest version.

Table of contents:


npm install --save localize-router


In order to use localize-router you must initialize it with following information:

  • Available languages/locales
  • Prefix for route segment translations
  • Routes to be translated

Initialize module

Module can be initialized either using static file or manually by passing necessary values.

Http loader

In order to use Http loader for config files, you must include localize-router-http-loader package and use its LocalizeRouterHttpLoader.

import {BrowserModule} from "@angular/platform-browser";
import {NgModule} from '@angular/core';
import {Location} from '@angular/common';
import {HttpClientModule, HttpClient} from '@angular/common/http';
import {TranslateModule} from '@ngx-translate/core';
import {LocalizeRouterModule} from 'localize-router';
import {LocalizeRouterHttpLoader} from 'localize-router-http-loader';
import {RouterModule} from '@angular/router';

import {routes} from './app.routes';

  imports: [
    LocalizeRouterModule.forRoot(routes, {
      parser: {
        provide: LocalizeParser,
        useFactory: (translate, location, settings, http) =>
            new LocalizeRouterHttpLoader(translate, location, settings, http),
        deps: [TranslateService, Location, LocalizeRouterSettings, HttpClient]
  bootstrap: [AppComponent]
export class AppModule { }

More details are available on localize-router-http-loader.

If you are using child modules or routes you need to initialize them with forChild command:

  imports: [
  declarations: [ChildComponent]
export class ChildModule { }

Initialization config

Apart from providing routes which are mandatory, and parser loader you can provide additional configuration for more granular setting of localize router. More information at LocalizeRouterConfig.

Manual initialization

With manual initialization you need to provide information directly:

LocalizeRouterModule.forRoot(routes, {
    parser: {
        provide: LocalizeParser,
        useFactory: (translate, location, settings) =>
            new ManualParserLoader(translate, location, settings, ['en','de',...], 'YOUR_PREFIX'),
        deps: [TranslateService, Location, LocalizeRouterSettings]

Server side initialization

In order to use server side initialization in isomorphic/universal projects you need to create loader similar to this:

export class LocalizeUniversalLoader extends LocalizeParser {
   * Gets config from the server
   * @param routes
  public load(routes: Routes): Promise<any> {
    return new Promise((resolve: any) => {
      let data: any = JSON.parse(fs.readFileSync(`assets/locales.json`, 'utf8'));
      this.locales = data.locales;
      this.prefix = data.prefix;

export function localizeLoaderFactory(translate: TranslateService, location: Location, settings: LocalizeRouterSettings) {
  return new LocalizeUniversalLoader(translate, location, settings);

Don't forget to create similar loader for ngx-translate as well:

export class TranslateUniversalLoader implements TranslateLoader {
   * Gets the translations from the server
   * @param lang
   * @returns {any}
  public getTranslation(lang: string): Observable<any> {
    return Observable.create(observer => {
      observer.next(JSON.parse(fs.readFileSync(`src/assets/locales/${lang}.json`, 'utf8')));
export function translateLoaderFactory() {
  return new TranslateUniversalLoader();

Since node server expects to know which routes are allowed you can feed it like this:

let fs = require('fs');
let data: any = JSON.parse(fs.readFileSync(`src/assets/locales.json`, 'utf8'));

app.get('/', ngApp);
data.locales.forEach(route => {
  app.get(`/${route}`, ngApp);
  app.get(`/${route}/*`, ngApp);

Working example can be found here.

How it works

Localize router intercepts Router initialization and translates each path and redirectTo path of Routes. The translation process is done with ngx-translate. In order to separate router translations from normal application translations we use prefix. Default value for prefix is ROUTES..

'home' -> 'ROUTES.home'

Upon every route change Localize router kicks in to check if there was a change to language. Translated routes are prepended with two letter language code:

http://yourpath/home -> http://yourpath/en/home

If no language is provided in the url path, application uses:

  • cached language in LocalStorage (browser only) or
  • current language of the browser (browser only) or
  • first locale in the config

Make sure you therefore place most common language (e.g. 'en') as a first string in the array of locales.

Note that localize-router does not redirect routes like my/route to translated ones e.g. en/my/route. All routes are prepended by currently selected language so route without language is unknown to Router.

Excluding routes

Sometimes you might have a need to have certain routes excluded from the localization process e.g. login page, registration page etc. This is possible by setting flag skipRouteLocalization on route's data object.

let routes = [
  // this route gets localized
  { path: 'home', component: HomeComponent },
  // this route will not be localized
  { path: 'login', component: LoginComponent, data: { skipRouteLocalization: true } }

Note that this flag should only be set on root routes. By excluding root route, all its sub routes are automatically excluded. Setting this flag on sub route has no effect as parent route would already have or have not language prefix.

ngx-translate integration

LocalizeRouter depends on ngx-translate core service and automatically initializes it with selected locales. Following code is run on LocalizeParser init:

this.translate.setDefaultLang(cachedLanguage || languageOfBrowser || firstLanguageFromConfig);
// ...
this.translate.use(languageFromUrl || cachedLanguage || languageOfBrowser || firstLanguageFromConfig);

Both languageOfBrowser and languageFromUrl are cross-checked with locales from config.


LocalizeRouterPipe is used to translate routerLink directive's content. Pipe can be appended to partial strings in the routerLink's definition or to entire array element:

<a [routerLink]="['user', userId, 'profile'] | localize">{{'USER_PROFILE' | translate}}</a>
<a [routerLink]="['about' | localize]">{{'ABOUT' | translate}}</a>

Root routes work the same way with addition that in case of root links, link is prepended by language. Example for german language and link to 'about':

'/about' | localize -> '/de/über'


Routes can be manually translated using LocalizeRouterService. This is important if you want to use router.navigate for dynamical routes.

class MyComponent {
    constructor(private localize: LocalizeRouterService) { }

    myMethod() {
        let translatedPath: any = this.localize.translateRoute('about/me');
        // do something with translated path
        // e.g. this.router.navigate([translatedPath]);


In order to use Ahead-Of-Time compilation any custom loaders must be exported as functions. This is the implementation currently in the solution:

export function localizeLoaderFactory(translate: TranslateService, location: Location, http: Http) {
  return new StaticParserLoader(translate, location, http);




  • forRoot(routes: Routes, config: LocalizeRouterConfig = {}): ModuleWithProviders: Main initializer for localize router. Can provide custom configuration for more granular settings.
  • forChild(routes: Routes): ModuleWithProviders: Child module initializer for providing child routes.



  • parser: Provider for loading of LocalizeParser. Default value is StaticParserLoader.
  • useCachedLang: boolean. Flag whether default language should be cached. Default value is true.
  • alwaysSetPrefix: boolean. Flag whether language should always prefix the url. Default value is true.
    When value is false, prefix will not be used for for default language (this includes the situation when there is only one language).
  • cacheMechanism: CacheMechanism.LocalStorage || CacheMechanism.Cookie. Default value is CacheMechanism.LocalStorage.
  • cacheName: string. Name of cookie/local store. Default value is LOCALIZE_DEFAULT_LANGUAGE.
  • defaultLangFunction: (languages: string[], cachedLang?: string, browserLang?: string) => string. Override method for custom logic for picking default language, when no language is provided via url. Default value is undefined.



  • routerEvents: An EventEmitter to listen to language change event
    localizeService.routerEvents.subscribe((language: string) => {
      // do something with language
  • parser: Used instance of LocalizeParser
    let selectedLanguage = localizeService.parser.currentLang;


  • translateRoute(path: string | any[]): string | any[]: Translates given path. If path starts with backslash then path is prepended with currently set language.
    localizeService.translateRoute('/'); // -> e.g. '/en'
    localizeService.translateRoute('/about'); // -> '/de/uber' (e.g. for German language)
    localizeService.translateRoute('about'); // -> 'uber' (e.g. for German language)
  • changeLanguage(lang: string, extras?: NavigationExtras, useNavigateMethod?: boolean): Translates current url to given language and changes the application's language. extras will be passed down to Angular Router navigation methods. userNavigateMethod tells localize-router to use navigate rather than navigateByUrl method.
    For german language and route defined as :lang/users/:user_name/profile
    yoursite.com/en/users/John%20Doe/profile -> yoursite.com/de/benutzer/John%20Doe/profil



  • locales: Array of used language codes
  • currentLang: Currently selected language
  • routes: Active translated routes
  • urlPrefix: Language prefix for current language. Empty string if alwaysSetPrefix=false and currentLang is same as default language.


  • translateRoutes(language: string): Observable<any>: Translates all the routes and sets language and current language across the application.
  • translateRoute(path: string): string: Translates single path
  • getLocationLang(url?: string): string: Extracts language from current url if matching defined locales


Licensed under MIT

If you find any bugs or have a feature request, please open an issue on github!

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