Firebase Auth: How can I detect that firebase trying to auto signIn current user?

问题

I'm using firebase.auth().onAuthStateChanged(...) in browser to detect that user is signed in and on every page load firebase trying to signIn current user (probably based on stored token in IndexDB). I need to detect when firebase trying automatically login current, so I can show loader instead of login form.

Issue:

1. User sees login form (not touching anything)
2. firebase automatically signin this user based on last token stored in IndexDB (it takes near 1 - 1.5 seconds) on this step I want to know about this and show loader to user
3. User thinks that he need to fill login form
4. After 1 - 1.5 seconds, triggered onAuthStateChanged and login form disappears
5. User little bit confused why he saw login form for those 1 - 1.5 seconds without any loader or notification that app trying to sigin him automatically

回答1:

I'm using the following code in my app to know whether user is already signed in or not. I don't know how to do it on browser but I hope you will get little idea by this.

    FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();

    FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();

    if(user!=null){
        startActivity(new Intent(MainActivity.this, MainMenu.class));
        this.finish();
    }

来源：https://stackoverflow.com/questions/59420760/firebase-auth-how-can-i-detect-that-firebase-trying-to-auto-signin-current-user