How to Link Multiple Auth Providers to an Firebase Account?

Question

I am unable to to sucessfully to do , I followed the following steps as instructed on Firebase Docs:

1. Signed in use using existing auth provider(my case:facebook).
2. Complete the sign-in flow for the new authentication provider up to, but not including, calling one of the Auth.signInWith methods.(my case: i want to link email & password and Google OAUth). So this is the step i'm unclear about, I created a new provider using var provider = new firebase.auth.GoogleAuthProvider(); and I did not do Firebase.auth().signInWithPopup(provider) .
3. Then to get authcredential for google I run var credential = firebase.auth.GoogleAuthProvider.credential( googleUser.getAuthResponse().id_token); (I get an undefined googleUser error) this error seems appropriate since I have not signed in using Google Oauth but thats what the 2nd steps states(not to signin)
4. And then this command to link with the current user who is on a Facebook Provider auth.currentUser.link(credential)

My understanding is that currentUser needs to be linked to my existing Provider(Facebook). It seems that credential variable for google is never computed. Anyone with a functional code example would really help.

Answer 1

If you want to manually link a google and email/pass account to existing facebook only firebase user, you can do the following: First, the user should be signed in to Facebook. Link the google user:

var provider = new firebase.auth.GoogleAuthProvider();
auth.currentUser.linkWithPopup(provider);

Then link the email/pass account:

auth.currentUser.linkWithCredential(firebase.auth.EmailAuthProvider.credential(auth.currentUser.email, 'password'))

All these accounts to be linked must be new and not already linked.