clojurescript drag and drop

boot.cljs

(defn handle-file-select [evt]
  (.stopPropagation evt)
  (.preventDefault evt)
  (let [files (.-files (.-dataTransfer evt))]
    (dotimes [i (.-length files)]
      (let [rdr (js/FileReader.)
            the-file (aget files i)]
        (set! (.-onload rdr)
              (fn [e]
                (let [file-content (.-result (.-target e))
                      file-name (if (= ";;; " (.substr file-content 0 4))
                                  (let [idx (.indexOf file-content "\n\n")]
                                    (.log js/console idx)
                                    (.slice file-content 4 idx))
                                  (.-name the-file))]
                  (.log js/console (str "file-name " file-name))
                  (.set storage file-name file-content)
                  (swap! list-of-code conj file-name))))
        (.readAsText rdr the-file)))))

(defn handle-drag-over [evt]
  (.stopPropagation evt)
  (.preventDefault evt)
  (set! (.-dropEffect (.-dataTransfer evt)) "copy"))

(defn set-up-drop-zone [id]
  (let [body (aget (.getElementsByTagName js/document "body") 0)
        zone (.createElement js/document "div")]
    (when-let [x (.getElementById js/document id)]
      (.removeChild body x))
    (set! (.-innerHTML zone) "Drop Here")
    (.setAttribute zone "id" id)
    (set! (.-position (.-style zone)) "absolute")
    (set! (.-top (.-style zone)) "0px")
    (set! (.-right (.-style zone)) "0px")
    (.appendChild body zone)
    (.addEventListener zone "dragover" handle-drag-over false)
    (.addEventListener zone "drop" handle-file-select false)))