Looking for logging into the Fb Button 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 Fb Button site. After that you can login as usual with your login credentials.
https://developers.facebook.com/docs/facebook-login/web/login-button%3Flocale%3Dja_JP
https://developers.facebook.com/docs/facebook-login/web/login-button/
https://developers.facebook.com/docs/facebook-login/web%3Flocale%3Dja_JP
https://tejitak.com/blog/%3Fp%3D248
https://stackoverflow.com/questions/3792231/fblogin-button-custom
https://qiita.com/nightyknite/items/10ab1853581265ef4bd6
https://qiita.com/ynunokawa/items/4c9147d2743d36e63832
https://www.youtube.com/watch%3Fv%3Dea9KyE78qKI
https://www.socialmediaexaminer.com/how-to-use-facebook-login-on-your-website/
https://www.back4app.com/docs/javascript/javascript-facebook-login
https://codeburst.io/node-js-rest-api-facebook-login-121114ee04d8
https://medium.com/%40KentaKodashima/ios-facebook-login-button-fc715818b410
https://www.observepoint.com/tag-database/facebook-login-button/