🎉 Add benchmark helper function (cljs only).

common/src/app/common/perf.cljc

@@ -19,3 +19,34 @@
 (defn measure
   [key]
   (- (timestamp) (get @measures key)))
+
+#?(:cljs
+   (defn benchmark
+     "A helper function for perform a unitari benchmark on JS/CLJS. It
+     uses browser native api so it only suitable to be executed in
+     browser."
+     [& {:keys [f warmup iterations name]
+         :or {iterations 10000}}]
+     (let [end-mark (str name ":end")]
+       (println "=> benchmarking:" name)
+       (println "--> warming up:" iterations)
+       (loop [i iterations]
+         (when (pos? i)
+           (f)
+           (recur (dec i))))
+       (println "--> benchmarking:" iterations)
+       (js/performance.mark name)
+       (loop [i iterations]
+         (when (pos? i)
+           (f)
+           (recur (dec i))))
+       (js/performance.measure end-mark name)
+       (let [[result] (js/performance.getEntriesByName end-mark)
+             duration (mth/precision (.-duration ^js result) 6)
+             avg      (mth/precision (/ duration iterations) 6)]
+         (println "--> TOTAL:" (str duration "ms") "AVG:" (str avg "ms"))
+         (js/performance.clearMarks name)
+         (js/performance.clearMeasures end-mark)
+         #js {:duration duration
+              :avg avg}))))
+