I'd rename some functions (like render-something into something-view), use reactions instead of functions to make it explicit that it's a reactive thing, and avoid derefing ratoms in JS handlers even when it seems to be OK to do so. And I would not use cljsjs nowadays, remove unused imports, replace mt/every with some hand-rolled impl to avoid an extra dependency just for that simple function, and would use reagent.core/atom via reagent/atom and not by shadowing the built-in atom. Other than than, seems alright.