Know what appId is used in firebase authentication

Question

I have 3 web applications in my firebase project, dev, stg and prod. In my front end project, I configured it so that each environment uses an appId. I want to be able to know from which appId is the user authenticated. Is that possible ?

Answer 1

You'll find this info in the FirebaseApp options object which, among others, contains the appId.

For example with the JS SDK v9:

import { getAuth, onAuthStateChanged } from "firebase/auth";

const auth = getAuth();
onAuthStateChanged(auth, (user) => {
  if (user) {
     console.log(auth.app.options.appId);
  } else {
    // User is signed out
    // ...
  }
});