so, by trying to run cljs in org-mode source blocks... ob-clojure makes use of cider, which connects to the clj repl. When I run a cljs project, I start 2 repls: one for clj and one for cljs. How can I tell org mode babel to connect to the cljs repl instead of the clj repl?

nice... one can choose the repl using M-x cider-toggle-connection-buffer RET

and set it to the cljs buffer. It is using rhino, not node, which means console is not available. (rhino uses print instead of console.log.) Maybe it's possible to let emacs use node instead of rhino, so one is more in line with the more common use case.