file uploader in cljs

upload-file.cljs

(defn file-input [on-result]
  [:input {:type "file"
           :on-change
           (fn [e]
             (let [f (first (array-seq (.. e -target -files)))
                   reader (js/FileReader.)]
               (aset reader "onload"
                     (fn [e]
                       (on-result (.. e -target -result))))
               (.readAsText reader f)))}])

;; same as above but with just a button

(defn $ [sel]
  (.querySelector js/document sel))

(defn file-input* 
  [{:keys [on-result text]}]
  (let [id (str (gensym))]
    (fn []
      [:span
       [:button {:on-click #(.click ($ (str "#" id)))} text]
       [:input {:id id
                :type "file"
                :style {:display :none}
                :on-change
                (fn [e]
                  (let [f (first (array-seq (.. e -target -files)))
                        reader (js/FileReader.)]
                    (aset reader "onload"
                          (fn [e]
                            (on-result (.. e -target -result))))
                    (.readAsText reader f)))}]])))