It's time to hop into Angular. From Solution Explorer, right-click to the /ClientApp/app/components/login/ folder and add a new login.externalproviders.component.ts file with the following content:
import { Component, Inject, OnInit, NgZone, PLATFORM_ID } from "@angular/core";import { isPlatformBrowser } from '@angular/common';import { HttpClient } from "@angular/common/http";import { Router } from "@angular/router";import { AuthService } from '../../services/auth.service';declare var window: any;@Component({ selector: "login-externalproviders", templateUrl: "./login.externalproviders.component.html"})export class LoginExternalProvidersComponent implements OnInit { externalProviderWindow :any; constructor( ...