Function beforeAuthStateChanged

beforeAuthStateChanged(
    auth: FirebaseAuthTypes.Module,
    callback: (user: User | null) => void,
    onAbort?: () => void,
): void
Adds a blocking callback that runs before an auth state change sets a new user.
Parameters
- auth: FirebaseAuthTypes.Module
  The Auth instance.
- callback: (user: User | null) => void
  A callback function to run before the auth state changes.
- OptionalonAbort: () => void
  Optional. A callback function to run if the operation is aborted.
Returns void
- Defined in auth/lib/modular/index.d.ts:63