Agular(ionic）で多言語化対応を行う

Ionic:

 Ionic CLI: 6.4.1 (/Users/myName/.nodebrew/node/v12.10.0/lib/node_modules/@ionic/cli)
   Ionic Framework  : @ionic/angular 5.1.1
   @angular-devkit/build-angular : 0.901.6
   @angular-devkit/schematics: 9.1.6
   @angular/cli   : 9.1.6
   @ionic/angular-toolkit : 2.2.0

Utility:
   cordova-res (update available: 0.14.0) : 0.9.0
   native-run (update available: 1.0.0)   : 0.2.9

System:
   NodeJS : v12.10.0 (/Users/masaya/.nodebrew/node/v12.10.0/bin/node)
   npm    : 6.14.2
   OS     : macOS Mojave

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

  "dependencies": {
    "@ngx-translate/core": "^12.1.2",
    "@ngx-translate/http-loader": "^4.0.0",

import {HttpClientModule, HttpClient} from '@angular/common/http';
import {TranslateModule} from '@ngx-translate/core';
・
  imports: [
    HttpClientModule,    
    TranslateModule.forRoot(),
  ],

import {HttpClientModule, HttpClient} from '@angular/common/http';
import {TranslateModule, TranslateLoader} from '@ngx-translate/core';
import {TranslateHttpLoader} from '@ngx-translate/http-loader';

export function createTranslateLoader(http: HttpClient) {
    return new TranslateHttpLoader(http, '../../assets/i18n/', '.json');
}

@NgModule({
    imports: [
      TranslateModule.forChild({
        loader: {
           provide: TranslateLoader,
           useFactory: (createTranslateLoader),
           deps: [HttpClient]
         }
      }),
    ],

import {TranslateService} from '@ngx-translate/core';

 constructor(
    private translate: TranslateService,
  ) {
    this.translate.setDefaultLang('en');
    this.translate.use('en');
}

<p>{{ 'HELLO' | translate }}</p>

{
  "HELLO": "こんにちはEnglish"
}

{
  "Main": "メイン",
  "File selection": "ファイルの選択",
  "1. Choose a file": "1. ファイルの選択",
  "Pick a file from your storage": "ストレージから選択",
  "Or take a new picture": "新しく写真を撮る",
  "2. Crop your image": "2. 写真の切り抜き",
  "select the area you want to analyze from the photo": "解析したいエリアを選択してください",
  "No ads 3 times if you watch a short video": "広告が3回表示されなくなります!",
  "Preparing for the analysis. Since this app uses service that need to be payed(from not you but me), an ad will be shown to you.":"安全な方法でアップロードします。 このアプリは有料のAPIを使用しているため、広告が表示されます。",
  "Analyzing.":"分析しています。"
}

+import {HttpClientModule, HttpClient} from '@angular/common/http';
+import {TranslateModule, TranslateLoader} from '@ngx-translate/core';
+import {TranslateHttpLoader} from '@ngx-translate/http-loader';

+export function createTranslateLoader(http: HttpClient) {
+    return new TranslateHttpLoader(http, '../assets/i18n/', '.json');
+}

@NgModule({
  declarations: [AppComponent],
  entryComponents: [],
  imports: [
+    TranslateModule.forRoot({
+      loader: {
+         provide: TranslateLoader,
+         useFactory: (createTranslateLoader),
+         deps: [HttpClient]
+       }
+    }),
  ],
  providers: [{ provide: RouteReuseStrategy, useClass: IonicRouteStrategy }],
  bootstrap: [AppComponent],
})
export class AppModule {}

+import {TranslateService} from '@ngx-translate/core';

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html',
  styleUrls: ['app.component.scss'],
})
export class AppComponent {

  constructor(
+    private translate: TranslateService,
  ) {
+      this.translate.setDefaultLang('en');
+      this.translate.use('en');
  }
}