What does Firebase's FacebookAuthProvider.addScope do?

Question

What does Firebase's FacebookAuthProvider.addScope do? Is it needed to retrieve an access token?

Answer 1

This is used to add Facebook OAuth 2.0 scopes such as: 'public_profile', 'email', 'user_likes', 'user_friends', etc. For example:

var provider = new firebase.auth.FacebookAuthProvider();
provider.addScope('user_friends');
provider.addScope('user_likes');
// This will open the Facebook sign in page and ask user to consent
// to the additional scopes.
firebase.auth().signInWithPopup(provider).then(function(result) {
  if (result.user) {
   // Additional user info like Facebook account url, gender, etc.
    console.log(result.additionalUserInfo.profile);
    // Facebook access token returned in the process
    // for the scopes requested.
    console.log(result.credential.accessToken);
  }
});