Use modern HTML5 and strict JS
This would mean adding <!DOCTYPE html> in the HTML and "use strict"; in the JS, and following modern best practices (e.g. use const and let instead of var).
Note that just adding a DOCTYPE breaks our layout, since it currently depends on "quirks mode".
Are we choosing any framework or just go wild with plain javascript?
I don't think we need a framework beyond ACE, if you consider it one?
I do not plan to add React or anything like that.
Yeah, it's pretty clear that mantaining the codebase in plain js is going to be difficult / time consuming so I'd suggest picking either Vue and React and start adapting the code. Do we have any preference between the two?
I'm familiar with React and not Vue, but could learn it, and would leave that decision up to @SelvinPL or whoever actually works on the transition.
@Rangi42 sorry, got too much work... Since I don't learn either I'm fine with React... Do you know good component library (to not reinvent menus, tabs etc.)