A bit outdated though e.g. for the first one, since 0.0.2060 cljs has grown (enable-console-print!) which sets print-fn to a wrapper around console.log. As a result, one can use all the usual clojure printing functions[0] and the output will be sent to the browser console.
[0] http://clojure.org/other_functions#Other%20Useful%20Function...