javascript - Angular 2 i18n dynamic/instant translation

Javascript - Angular 2 i18n dynamic/instant translation

To achieve dynamic or instant translation in an Angular 2+ application, you can utilize the ngx-translate library, which is a popular choice for internationalization (i18n) in Angular applications. This library allows you to dynamically switch languages and update translations without reloading the entire application. Below is a step-by-step guide on how to set up and use ngx-translate for dynamic translation in your Angular application.

Step 1: Install ngx-translate

First, you need to install ngx-translate/core and ngx-translate/http-loader via npm:

npm install @ngx-translate/core @ngx-translate/http-loader --save

Step 2: Configure ngx-translate in AppModule

In your main AppModule, configure ngx-translate to load translations dynamically using TranslateHttpLoader:

AppModule Configuration

import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { HttpClientModule, HttpClient } from '@angular/common/http'; import { TranslateModule, TranslateLoader } from '@ngx-translate/core'; import { TranslateHttpLoader } from '@ngx-translate/http-loader'; import { AppComponent } from './app.component'; // AoT requires an exported function for factories export function HttpLoaderFactory(http: HttpClient) { return new TranslateHttpLoader(http, './assets/i18n/', '.json'); } @NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, HttpClientModule, TranslateModule.forRoot({ loader: { provide: TranslateLoader, useFactory: HttpLoaderFactory, deps: [HttpClient] } }) ], providers: [], bootstrap: [AppComponent] }) export class AppModule { }

Step 3: Create Translation Files

Create translation JSON files for each language you want to support under assets/i18n/ directory. For example:

en.json:

{ "hello": "Hello", "goodbye": "Goodbye" }

fr.json:

{ "hello": "Bonjour", "goodbye": "Au revoir" }

Step 4: Use ngx-translate in Components

Component Template

Use the translate pipe to display translated content in your component template:

<div>{{ 'hello' | translate }}</div> <button (click)="switchLanguage('en')">English</button> <button (click)="switchLanguage('fr')">French</button>

Component Class

Handle language switching and other dynamic translation updates in your component class:

import { Component } from '@angular/core'; import { TranslateService } from '@ngx-translate/core'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { constructor(private translate: TranslateService) { // Set default language this.translate.setDefaultLang('en'); } switchLanguage(lang: string) { this.translate.use(lang); // Switch language dynamically } }

Step 5: Dynamic Translation

With ngx-translate, translations are updated dynamically without reloading the application:

  • When you call this.translate.use(lang) in your component, it switches the language immediately.
  • All instances of {{ 'key' | translate }} in your templates update to the new language automatically.

Additional Considerations

  • Loading Translations: Ensure translations are loaded once when the application starts. ngx-translate/http-loader fetches translation files dynamically, or you can preload translations if needed.

  • Localization: For more complex localization needs (e.g., formatting dates, numbers), extend ngx-translate or integrate with other libraries or services.

  • Performance: Manage translation loading and updates efficiently, especially for larger applications or dynamic content.

By following these steps, you can implement dynamic or instant translation in your Angular 2+ application using ngx-translate, providing a seamless user experience across different languages without the need for full page reloads. Adjust the setup and usage based on your specific application requirements and internationalization needs.

Examples

  1. Angular 2 dynamic translation using ngx-translate

    • Description: Implement dynamic translation in Angular 2 using ngx-translate for instant language switching.
    • Code:
      // app.module.ts import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { HttpClientModule, HttpClient } from '@angular/common/http'; import { TranslateModule, TranslateLoader } from '@ngx-translate/core'; import { TranslateHttpLoader } from '@ngx-translate/http-loader'; export function HttpLoaderFactory(http: HttpClient) { return new TranslateHttpLoader(http, './assets/i18n/', '.json'); } @NgModule({ imports: [ BrowserModule, HttpClientModule, TranslateModule.forRoot({ loader: { provide: TranslateLoader, useFactory: HttpLoaderFactory, deps: [HttpClient] } }) ], bootstrap: [AppComponent] }) export class AppModule { } 
      // app.component.ts import { Component } from '@angular/core'; import { TranslateService } from '@ngx-translate/core'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { constructor(private translate: TranslateService) { translate.setDefaultLang('en'); translate.use('en'); } switchLang(lang: string) { this.translate.use(lang); } } 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div>{{ 'HELLO' | translate }}</div>
    • Explanation: This code sets up ngx-translate in an Angular 2 application. It loads translations from JSON files (en.json, fr.json) located in assets/i18n/. The switchLang method allows dynamic language switching.

  2. Angular 2 dynamic translation with pipes

    • Description: Use Angular 2 pipes for dynamic translation of text content in the template.
    • Code:
      // app.module.ts (same as previous example) 
      // app.component.ts import { Component } from '@angular/core'; import { TranslateService } from '@ngx-translate/core'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { constructor(private translate: TranslateService) { translate.setDefaultLang('en'); translate.use('en'); } switchLang(lang: string) { this.translate.use(lang); } } 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div>{{ 'HELLO' | translate }}</div>
    • Explanation: This example is similar to the previous one but emphasizes using Angular 2 pipes ({{ 'HELLO' | translate }}) directly in the template for dynamic translation.

  3. Angular 2 dynamic translation with interpolation

    • Description: Perform dynamic translation with interpolated values in Angular 2 using ngx-translate.
    • Code:
      // app.module.ts (same as previous examples) 
      // app.component.ts import { Component } from '@angular/core'; import { TranslateService } from '@ngx-translate/core'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { name = 'John'; constructor(private translate: TranslateService) { translate.setDefaultLang('en'); translate.use('en'); } switchLang(lang: string) { this.translate.use(lang); } } 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div>{{ 'HELLO' | translate:{ name: name } }}</div>
    • Explanation: In this example, the translation key HELLO is interpolated with the name variable in the template using ngx-translate's interpolation feature.

  4. Angular 2 dynamic translation with service

    • Description: Implement dynamic translation using a service to fetch translated content in Angular 2.
    • Code:
      // translation.service.ts import { Injectable } from '@angular/core'; import { TranslateService } from '@ngx-translate/core'; @Injectable({ providedIn: 'root' }) export class TranslationService { constructor(private translate: TranslateService) { translate.setDefaultLang('en'); translate.use('en'); } getTranslation(key: string): string { return this.translate.instant(key); } switchLang(lang: string) { this.translate.use(lang); } } 
      // app.component.ts import { Component } from '@angular/core'; import { TranslationService } from './translation.service'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { name = 'John'; constructor(private translationService: TranslationService) { } switchLang(lang: string) { this.translationService.switchLang(lang); } } 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div>{{ translationService.getTranslation('HELLO') }}</div>
    • Explanation: This code structure separates translation logic into a service (TranslationService), allowing components to fetch translations dynamically.

  5. Angular 2 dynamic translation with HTML attribute

    • Description: Use HTML attributes for dynamic translation in Angular 2 templates using ngx-translate.
    • Code:
      // app.module.ts (same as previous examples) 
      // app.component.ts (same as previous examples) 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div translate>HELLO</div>
    • Explanation: The translate attribute in the HTML tag (<div translate>HELLO</div>) automatically translates the content using ngx-translate.

  6. Angular 2 dynamic translation with pluralization

    • Description: Perform dynamic translation with pluralization support in Angular 2 using ngx-translate.
    • Code:
      // app.module.ts (same as previous examples) 
      // app.component.ts (same as previous examples) 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div>{{ 'ITEM_COUNT' | translate: { count: itemCount } }}</div>
    • Explanation: This example demonstrates translating a key (ITEM_COUNT) with pluralization, using the count variable for dynamic content.

  7. Angular 2 dynamic translation with async pipe

    • Description: Use Angular 2's async pipe for dynamic translation with observable data in ngx-translate.
    • Code:
      // app.module.ts (same as previous examples) 
      // app.component.ts import { Component } from '@angular/core'; import { TranslateService } from '@ngx-translate/core'; import { Observable } from 'rxjs'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { name$: Observable<string>; constructor(private translate: TranslateService) { translate.setDefaultLang('en'); translate.use('en'); this.name$ = this.translate.get('NAME'); } switchLang(lang: string) { this.translate.use(lang); this.name$ = this.translate.get('NAME'); } } 
      <!-- app.component.html --> <button (click)="switchLang('en')">English</button> <button (click)="switchLang('fr')">French</button> <div>{{ name$ | async }}</div>
    • Explanation: This code fetches translated content (NAME) as an observable (name$) using translate.get() and displays it using the async pipe in the template.

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