Well, my updated JavaScript course added a section on var/let/const (which I kinda knew already), but I didn't know about the naming conventions, for example UPPERCASE for const.
Just learned that you should always pay attention to the passing arguments in render methods. I have "render_to_string" method inside JSON answer in Rails controller. And I forgot to pass "locals" with my variable there. Either this or use @instant variables inside partial views. But it' better to always pass.
I'm currently reading Atomic Habits. I learned that habits are highly dependent on your environment. If you want to build or break habits, changing your environment is a key strategy.