Looking for logging into the Facebook Only site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Facebook Only site. After that you can login as usual with your login credentials.
https://en-gb.facebook.com/
https://developers.facebook.com/docs/facebook-login/permissions/overview/
https://developers.facebook.com/blog/post/2018/06/08/enforce-https-facebook-login/
https://developers.facebook.com/docs/facebook-login/permissions/%3Flocale%3Dja_JP
https://www.quora.com/What-are-the-risks-of-using-only-Facebook-login-for-your-website
https://stackoverflow.com/questions/30980785/facebook-javascript-sdk-login-https-works-only-if-you-login-twice
https://stackoverflow.com/questions/27952623/facebook-login-for-group-members
https://www.youtube.com/watch%3Fv%3DokRZX7ZxTFU
https://ux.stackexchange.com/questions/64559/facebook-twitter-login-only-vs-facebook-twitter-signup-and-login-separately
https://www.theregister.co.uk/2018/05/04/delete_facebook_login/
https://auth0.com/docs/connections/social/facebook
https://firebase.google.com/docs/auth/web/facebook-login
https://www.sammyk.me/best-practice-for-facebook-login-with-the-javascript-sdk-and-php-sdk-v4-1