passport.use(
        new Strategy(
            {
                clientID: '<clientID>',
                clientSecret: '<ClientSecret>',
                callbackURL: 'http://myapp/authenticated'
            },
            (accessToken, refreshToken, profile, cb) => {
                return cb(null, profile);
            }
        )
    );

    this.config.app.get(
        '/login',
        passport.authenticate('github', {
            scope: [
                'user',
                'notifications',
                'gist',
                'repo',
                'admin:org',
                'admin:public_key',
                'admin:repo_hook',
                'admin:org_hook'
            ]
        })
    );

    this.config.app.get(
        '/authenticated',
        passport.authenticate('github', {
            successRedirect: '/home',
            failureRedirect: '/signin',

            session: false
        }),
        (req, res) => {
            res.redirect('/home');
        }
    );
}

public async login(username: string, password: string) {
    const httpOptions = {
        headers: new HttpHeaders({
            'Content-Type': 'application/json'
        })
    };

    const result = await this.http
        .get<any>('/login', httpOptions)
        .toPromise();

404 https://github.com/login/oauth/authorize?response_type=code&redirect....

Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://myapp' is therefore not allowed access.

public async login(username: string, password: string) {
    window.open('/login', '_self');