Global variables are stored outside of the current function, but can be used across functions or even between the main code and a function. It works the same way as a regular variable.
Global variables are stored in the global scope of code. They can be accessed across functions and even between the main code and functions.
gv.cats = 5 will create a global variable called “cats” with a value of 5.
Becase we are accessing a outside scope, when setting or loading info using a global variable any sub set variables you are loading must also be from within the same global scope. So for example you cant use this gv.users_loggedin[v.user_id]=true will not save, it would need v.user_id in the same scope as global, so setting a global on user_id first will allow it to work in the following case.
gv.justforthis_user_id=v.user_id
gv.users_loggedin[gv.justforthis_user_id]=true