I'm trying to program a check off calendar/task app. Want I want to achieve is that, whenever I click on a box it should be checked off, show it's crossed off ( Day is crossed off ). And then I want to store this is in my session.

What I'm thinking about doing is setting a boolean variable in the HTML to true and then send it with the session. So it can be remembered when I reload the page. But I still see the problem of letting the server-side know that this boolean has changed.
Is this the way to achieve this? Is there some better way?

Controlling my server-side is Nodejs and I'm using the ejs templating. I'm using express-session to manage my session.

Thanks in advance!