...

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

  @i18n('key.to.text.in.file', 'initial and fallback text value with optional [placeholder]', 'optional placeholder')
  name!: string;

  descriptionLabel!: string;

  constructor() { ... }

  ...
}

  setI18n() {
    this.descriptionLabel = getI18nText(
      'key.to.text.in.file',
      'Gewicht: [placeholder] kg',
      100
    );
  }