The user IDs don't really encode any information. They are just there to associate a history with a user. When a user visits the page there's a check to see if

The user IDs don't really encode any information. They are just there to associate a history with a user. When a user visits the page there's a check to see if they have a user id in local storage, if not then it gets the current time and hashes it to produce a new userId which is stored in local storage for future use.