When debugging Reagent components, I printed data structures to the browser's console. I formatted them with my mind.
My colleague Marten did too. We have both stopped. The reason? Marten gave birth to this beauty:
(defn debug-panel "Debug panel, pretty prints any data you pass in on the screen." [d] [:pre (with-out-str (cljs.pprint/pprint d))])
debug-panel component can be included within a HTML-tag on the page like this:
[debug-panel <data structure>].
It displays the data structure on the page, nicely formatted.