It is possible to modify the state from js script?

[nicolalandro]

I want to implement a simple login, and I want to create two js function to read and write cookie.
I see that globalThis.core.getUserState() get the session state but how to set some variables?
Also a code like state.call_frontend_function("mymodule", "sendAlert", ["Bob"]) does return None and not what a js function can return.

Any suggestion for login implementation or in general to interact with js scripts? Must I create a component in this case?