An Angular library to translate texts, dates and numbers
This library is for localization of Angular apps. It allows, in addition to translation, to format dates and numbers through Internationalization API
npm install angular-l10n --save
You can find a complete sample app here and a live example on StackBlitz
Create the configuration:
export const l10nConfig: L10nConfig = {
format: 'language-region',
providers: [
{ name: 'app', asset: i18nAsset }
],
cache: true,
keySeparator: '.',
defaultLocale: { language: 'en-US', currency: 'USD', timeZone: 'America/Los_Angeles' },
schema: [
{ locale: { language: 'en-US', currency: 'USD', timeZone: 'America/Los_Angeles', units: { 'length': 'mile' } }, dir: 'ltr', text: 'United States' },
{ locale: { language: 'it-IT', currency: 'EUR', timeZone: 'Europe/Rome', units: { 'length': 'kilometer' } }, dir: 'ltr', text: 'Italia' }
],
};
const i18nAsset = {
'en-US': {
greeting: 'Hello world!',
whoIAm: 'I am {{name}}',
devs: {
one: 'One software developer',
other: '{{value}} software developers'
}
},
'it-IT': {
greeting: 'Ciao mondo!',
whoIAm: 'Sono {{name}}',
devs: {
one: 'Uno sviluppatore software',
other: "{{ value }} sviluppatori software"
}
}
};
Do you only need to localize and not translate? Give the
providers
an empty array, but provide the supported locales in theschema
anyway
Import the modules and the configuration:
@NgModule({
...
imports: [
...
L10nTranslationModule.forRoot(l10nConfig),
L10nIntlModule
],
bootstrap: [AppComponent]
})
export class AppModule { }
<!-- translate pipe -->
<p>{{ 'greeting' | translate:locale.language }}</p>
<!-- translate pipe with attributes -->
<p title="{{ 'greeting' | translate:locale.language }}">{{ 'greeting' | translate:locale.language }}</p>
<!-- Hello world! -->
<!-- translate pipe with params -->
<p>{{ 'whoIAm' | translate:locale.language:{ name: 'Angular l10n' } }}</p>
<!-- I am Angular l10n -->
<!-- l10nDate pipe -->
<p>{{ today | l10nDate:locale.language:{ dateStyle: 'full', timeStyle: 'short' } }}</p>
<!-- Wednesday, November 10, 2021, 2:17 PM -->
<!-- l10nTimeAgo pipe -->
<p>{{ -4 | l10nTimeAgo:locale.language:'second':{ numeric:'always', style:'long' } }}</p>
<!-- 4 seconds ago -->
<!-- l10nNumber pipe -->
<p>{{ 1000 | l10nNumber:locale.language:{ digits: '1.2-2', style: 'currency' } }}</p>
<!-- $1,000.00 -->
<!-- l10nNumber pipe with convert function -->
<p>{{ 1000 | l10nNumber:locale.language:{ digits: '1.2-2', style: 'currency' }:locale.currency:convertCurrency:{ rate: 1.16 } }}</p>
<!-- $1,160.00 -->
<!-- l10nNumber pipe with unit & convert function -->
<p>{{ 1 | l10nNumber:locale.language:{ digits: '1.0-2', style: 'unit', unit: locale.units['length'] }:undefined:convertLength }}</p>
<!-- 0.62 mi -->
<!-- l10nPlural pipe -->
<p>{{ 2 | l10nPlural:locale.language:'devs':{ type: 'cardinal' } }}</p>
<!-- 2 software developers -->
<!-- l10nDisplayNames pipe -->
<p>{{ 'en-US' | l10nDisplayNames:locale.language:{ type: 'language' } }}</p>
<!-- American English -->
Pure pipes need to know when the locale changes. So import L10nLocale
injection token in every component that uses them:
export class PipeComponent {
constructor(@Inject(L10N_LOCALE) public locale: L10nLocale) { }
}
or if you prefer the shortest inject
function:
export class PipeComponent {
locale = inject(L10N_LOCALE);
}
An optional function to convert the value of numbers, with the same value, locale and destructured optional parameters in the signature:
export const convertCurrency = (value: number, locale: L10nLocale, rate: number) => {
switch (locale.currency) {
case "USD":
return value * rate;
default:
return value;
}
};
To support this strategy, there is an Async
version of each pipe, which recognizes by itself when the locale changes:
<p>{{ 'greeting' | translateAsync }}</p>
<!-- l10nTranslate directive -->
<p l10nTranslate>greeting</p>
<!-- l10nTranslate directive with attributes -->
<p l10n-title title="greeting" l10nTranslate>greeting</p>
<!-- l10nTranslate directive with params -->
<p [params]="{ name: 'Angular l10n' }" l10nTranslate>whoIAm</p>
<!-- l10nDate directive -->
<p [options]="{ dateStyle: 'full', timeStyle: 'short' }" l10nDate>{{ today }}</p>
<!-- l10nTimeAgo directive -->
<p [options]="{ numeric:'always', style:'long' }" unit="second" l10nTimeAgo>-4</p>
<!-- l10nNumber directive -->
<p [options]="{ digits: '1.2-2', style: 'currency' }" l10nNumber>1000</p>
<!-- l10nNumber directive with convert function -->
<p [options]="{ digits: '1.2-2', style: 'currency' }" [convert]="convertCurrency" [convertParams]="{ rate: 1.16 }" l10nNumber>1000</p>
<!-- l10nNumber directive with unit & convert function -->
<p [options]="{ digits: '1.0-2', style: 'unit', unit: locale.units['length'] }" [convert]="convertLength" l10nNumber>1</p>
<!-- l10nPlural directive -->
<p [options]="{ type: 'cardinal' }" prefix="devs" l10nPlural>2</p>
<!-- l10nDisplayNames directive -->
<p [options]="{ type: 'language' }" l10nDisplayNames>en-US</p>
You can dynamically change parameters and expressions values as with pipes, but not in attributes.
L10nTranslationService
provides an onChange
event, which is fired whenever the locale changes.
export class ApiComponent implements OnInit {
constructor(private translation: L10nTranslationService, private intl: L10nIntlService) { }
ngOnInit() {
this.translation.onChange().subscribe({
next: (locale: L10nLocale) => {
// Texts
this.greeting = this.translation.translate('greeting');
this.whoIAm = this.translation.translate('whoIAm', { name: 'Angular l10n' });
// Dates
this.formattedToday = this.intl.formatDate(this.today, { dateStyle: 'full', timeStyle: 'short' });
this.formattedTimeAgo = this.intl.formatRelativeTime(-4, 'second', { numeric: 'always', style: 'long' });
// Numbers
this.formattedValue = this.intl.formatNumber(
1000,
{ digits: '1.2-2', style: 'currency' },
undefined,
undefined,
convertCurrency,
{ rate: 1.16 }
);
this.formattedLength = this.intl.formatNumber(
1,
{ digits: '1.0-2', style: 'unit', unit: locale.units['length'] },
undefined,
undefined,
convertLength
);
this.formattedOnePlural = this.intl.plural(1, 'devs', { type: 'cardinal' });
this.formattedOtherPlural = this.intl.plural(2, 'devs', { type: 'cardinal' });
}
});
}
}
L10nIntlService
provides methods for all Intl APIs, including Collator & ListFormat.
You can change the locale at runtime at any time by calling the setLocale
method of L10nTranslationService
:
<button *ngFor="let item of schema" (click)="setLocale(item.locale)">{{ item.locale.language | l10nDisplayNames:locale.language:{ type: 'language' } }}</button>
export class AppComponent {
schema = this.l10nConfig.schema;
constructor(@Inject(L10N_CONFIG) private l10nConfig: L10nConfig, private translation: L10nTranslationService) { }
setLocale(locale: L10nLocale): void {
this.translation.setLocale(locale);
}
}
It is not mandatory to use the schema provided during the configuration: it is possible to set the language or currency, or any other property of L10nLocale
separately.
The following features can be customized. You just have to implement the indicated class-interface and pass the token during configuration.
E.g.
@Injectable() export class HttpTranslationLoader implements L10nTranslationLoader {
private headers = new HttpHeaders({ 'Content-Type': 'application/json' });
constructor(@Optional() private http: HttpClient) { }
public get(language: string, provider: L10nProvider): Observable<{ [key: string]: any }> {
const url = `${provider.asset}-${language}.json`;
const options = {
headers: this.headers,
params: new HttpParams().set('v', provider.options.version)
};
return this.http.get(url, options);
}
}
export const l10nConfig: L10nConfig = {
...
providers: [
{ name: 'app', asset: './assets/i18n/app', options: { version: '1.0.0' } },
],
...
};
@NgModule({
...
imports: [
...
L10nTranslationModule.forRoot(
l10nConfig,
{
translationLoader: HttpTranslationLoader
}
)
],
...
})
export class AppModule { }
By default, the library does not store the locale. To store it implement the L10nStorage
class-interface using what you need, such as web storage or cookie, so that the next time the user has the locale he selected.
By default, the library attempts to set the locale using the user's browser language, before falling back on the default locale. You can change this behavior by implementing the L10nUserLanguage
class-interface, for example to get the language via server.
By default, you can only pass JavaScript objects as translation data provider. To implement a different loader, you can implement the L10nTranslationLoader
class-interface, as in the example above.
You can enable translation fallback during configuration:
export const l10nConfig: L10nConfig = {
...
fallback: true,
...
};
By default, the translation data will be merged in the following order:
'language'
'language[-script]'
'language[-script][-region]'
To change it, implement the L10nTranslationFallback
class-interface.
By default, the library only parse the params. L10nTranslationHandler
is the class-interface to implement to modify the behavior.
If a key is not found, the same key is returned. To return a different value, you can implement the L10nMissingTranslationHandler
class-interface.
If you need to preload some data before initialization of the library, you can implement the L10nLoader
class-interface:
@Injectable() export class AppLoader implements L10nLoader {
constructor(private translation: L10nTranslationService) { }
public async init(): Promise<void> {
await ... // Some custom data loading action
await this.translation.init();
}
}
@NgModule({
imports: [
L10nTranslationModule.forRoot(
l10nConfig,
{
loader: AppLoader
}
),
],
})
or if you are using L10nRouting
:
@Injectable() export class AppRoutingLoader implements L10nLoader {
constructor(private routing: L10nRoutingService, private translation: L10nTranslationService) { }
public async init(): Promise<void> {
await ... // Some custom data loading action
await this.routing.init();
await this.translation.init();
}
}
@NgModule({
imports: [
L10nRoutingModule.forRoot({
loader: AppRoutingLoader
})
],
})
There are two directives, that you can use with Template driven or Reactive forms: l10nValidateNumber
and l10nValidateDate
. To use them, you have to implement the L10nValidation
class-interface, and import it with the validation module:
@Injectable() export class LocaleValidation implements L10nValidation {
constructor(@Inject(L10N_LOCALE) private locale: L10nLocale) { }
public parseNumber(value: string, options?: L10nNumberFormatOptions, language = this.locale.numberLanguage || this.locale.language): number | null {
...
}
public parseDate(value: string, options?: L10nDateTimeFormatOptions, language = this.locale.dateLanguage || this.locale.language): Date | null {
...
}
}
@NgModule({
...
imports: [
...
L10nValidationModule.forRoot({ validation: LocaleValidation })
],
...
})
export class AppModule { }
You can enable the localized routing importing the routing module after others:
@NgModule({
...
imports: [
...
L10nRoutingModule.forRoot()
],
...
})
export class AppModule { }
A prefix containing the language is added to the path of each navigation, creating a semantic URL:
baseHref/[language][-script][-region]/path
https://example.com/en/home
https://example.com/en-US/home
If the localized link is called, the locale is also set automatically.
To achieve this, the router configuration in your app is not rewritten: the URL is replaced, in order to provide the different localized contents both to the crawlers and to the users that can refer to the localized links.
If you don't want a localized routing for default locale, you can enable it during the configuration:
export const l10nConfig: L10nConfig = {
...
defaultRouting: true
};
You can change the localized path, implementing the L10nLocation
class-interface, and import it with the routing module:
@Injectable() export class AppLocation implements L10nLocation {
public path(): string {
...
}
public parsePath(path: string): string | null {
...
}
public getLocalizedSegment(path: string): string | null {
...
}
public toLocalizedPath(language: string, path: string): string {
...
}
}
@NgModule({
...
imports: [
...
L10nRoutingModule.forRoot({ location: AppLocation })
],
...
})
export class AppModule { }
If you want to add new providers to a lazy loaded module, you can use L10nResolver
in your routing module:
const routes: Routes = [
...
{
path: 'lazy',
loadChildren: () => import('./lazy/lazy.module').then(m => m.LazyModule),
resolve: { l10n: L10nResolver },
data: {
l10nProviders: [{ name: 'lazy', asset: './assets/i18n/lazy', options: { version: '1.0.0' } }]
}
}
];
Always import the modules you need:
@NgModule({
declarations: [LazyComponent],
imports: [
...
L10nTranslationModule
]
})
export class LazyModule { }
If you are bundling translation data using the default L10nTranslationLoader
, you can add translation providers to lazy modules by updating the configuration and calling the loadTranslation
method:
const i18nLazyAsset = { 'en-US': {...}, 'it-IT': {...} };
this.translation.addProviders([{ name: 'lazy', asset: i18nLazyAsset}]);
this.translation.loadTranslation([{ name: 'lazy', asset: i18nLazyAsset}]);
Enable caching during configuration if you want to prevent reloading of the already loaded translation data:
export const l10nConfig: L10nConfig = {
...
cache: true
};
If you need to preload some translation data, for example to use for missing values, L10nTranslationService
exposes the translation data in the data
attribute. You can merge data by calling the addData
method:
@Injectable() export class AppLoader implements L10nLoader {
constructor(private translation: L10nTranslationService, private translationLoader: L10nTranslationLoader) { }
public async init(): Promise<void> {
await new Promise((resolve) => {
this.translationLoader.get('en-US', { name: 'app', asset: './assets/i18n/app', options: { version: '1.0.0' } })
.subscribe({
next: (data) => this.translation.addData(data, 'en-US'),
complete: () => resolve(null)
});
});
await this.translation.init();
}
}
Angular l10n types that it is useful to know:
L10nLocale
: contains a language, in the format language[-script][-region][-extension]
, where:
Optionally:
L10nFormat
: shows the format of the language to be used for translations. The supported formats are: 'language' | 'language-script' | 'language-region' | 'language-script-region'
. So, for example, you can have a language like en-US-u-ca-gregory-nu-latn
to format dates and numbers, but only use the en-US
for translations setting 'language-region'
L10nDateTimeFormatOptions
: the type of options used to format dates. Extends the Intl DateTimeFormatOptions
interface, replacing the dateStyle and timeStyle attributes. See DateTimeFormat for more details on available options
L10nNumberFormatOptions
: the type of options used to format numbers. Extends the Intl NumberFormatOptions
interface, adding the digits attribute. See NumberFormat for more details on available options
To format dates and numbers, this library uses Intl API
Current browser support:
If you need to support previous versions of browsers, or to use newest features see Format.JS
To use Intl in Node.js, check the support according to the version in the official documentation: Internationalization Support
You can find a complete sample app with @nguniversal/express-engine here
SSR doesn't work out of the box, so it is important to know:
src\app\universal-interceptor.ts
: used to handle absolute URLs for HTTP requests on the serversrc\app\l10n-config.ts
:AppStorage (implements L10nStorage)
: uses a cookie to store the locale client & server sideAppUserLanguage (implements L10nUserLanguage)
: server side, negotiates the language through acceptsLanguages
to get the user language when the app startsAngular v13 (Angular l10n v13.1.0)
Angular v12 (Angular l10n v12.0.1)
Angular v11 (Angular l10n v11.1.0)
Angular v10 (Angular l10n v10.1.2)
Angular v9 (Angular l10n v9.3.0)
Angular v8 (Angular l10n v8.1.2)
Angular v7 (Angular l10n v7.2.0)
Angular v6 (Angular l10n v5.2.0)
Angular v5 (Angular l10n v4.2.0)
Angular v4 (Angular l10n v3.5.2)
Angular v2 (Angular l10n v2.0.11)
First, install the packages & build the library:
npm install
npm run build:watch
Testing:
npm run test:watch
Serving the sample app:
npm start
Serving the sample ssr app:
npm run dev:ssr
MIT