How can I verify if an email address is already use by a provider (Google or Facebook)?

Question

In my web app I use login Firebase ( Google and Facebook ).

But I would like to prevent the user if their email address is already in use by Google or Facebook .

Example:

If my user would like connect with Google , their email address is user@example.com and after they would like to connect but with Facebook and his email address for Facebook is the same (user@example.com) .

How I can verify if the email address already exists?

Answer 1

Check out this links on firebase docs it should help you out with facebook login there are more examples on the site including that of google login

https://firebase.google.com/docs/auth/web/facebook-login#handling-account-exists-with-different-credential-errors