an example of how to load scripts in angular without polluting index.html

app.component.ts

...

@Component({
  ...
})
export class AppComponent implements OnInit{
  constructor(private  readonly http: HttpClient) {
  }

  ngOnInit() {
    this.http.jsonp('https://www.google.com/recaptcha/api.js?render=reCAPTCHA_site_key', 'callback')
      .subscribe(() => {});
  }
}

app.module.ts

...

@NgModule({
  ...
  imports: [
    ...
    HttpClientModule,
    HttpClientJsonpModule,
  ],
  ...
})
export class AppModule { }