Is node/backend required to save input on a site? [duplicate]

CONTEXT (OPTIONAL)

I know its a duplicate but the other posts didn't answer my problem.

I have a site running on github.io, which I would share but it is currently running a "prank" site and it's really dumb. I did it to test my knowledge and train web development.

I have yet to learn Node and Backend, I don't know much about it so I'm sorry if this seems like a bad question!

QUESTION BEGINS HERE

I have an array at my js file and I want the user to be able to submit strings to it, it does work but only until I refresh the page, only javascript, CSS and HTML are running, no Node, no Backend, is there a way to submit those changes permanently without backend?

edit: And, if I were to use backend, which tools should I be familiar with? I don't know much about server-side programming and client-side, only recently I discovered that there is a difference and I know that node is relevant to the server-side.

EDIT

I'm referring to this post that is about cookies and local storage, but from my understanding, cookies only save data on the client's machine, as do local storage, right?