ionic-framework/angular/test/test-app/src/main.ts

import { enableProdMode } from '@angular/core';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app/app.module';
import { environment } from './environments/environment';

if (environment.production) {
  enableProdMode();
}

document.addEventListener('DOMContentLoaded', () => {
  platformBrowserDynamic()
  .bootstrapModule(AppModule)
  .catch(err => console.error(err));
});