Convert a HTMLElement's dataset property into a ClojureScript map

DOMStringMap-to-map.cljs

;; DOMStringMap is the type of `HTMLElement.dataset` and contains the element's `data-*` attributes.

;; Implement the protocol used by the `cljs.core/js->clj` function.
(extend-type js/DOMStringMap
  IEncodeClojure
  (-js->clj [x {:keys [keywordize-keys]}]
    (let [keyfn (if keywordize-keys keyword identity)]
      (->> (.entries js/Object x)
           (reduce
             (fn [m [k v]] (assoc m (keyfn k) v))
             {})))))

;; Example uses:
(def some-element (.querySelector js/document "#foo"))
(js->clj (.-dataset some-element))
(js->clj (.-dataset some-element) :keywordize-keys true)