userID, which can be any string that uniquely identifies the user and is immutable throughout its lifetime.
A database primary key would make an ideal
userID. Conversely, something like username or emails is not recommended as those values may change overtime.
userIdis immutable once the account is created, however the
displayNamecan be updated at all times.
displayNameis passed, it will update the user directly.›
displayNameis passed, but secured mode is enabled, the values will be ignored.
updateCurrentUser:method which allows you to update information about current user.
observeFileand use it to display in your app later on. Here's an example in React: