create a download of some data in a clojurescript repl (eg. figwheel)

download.cljs

(defn download
  ; adapted from https://stackoverflow.com/a/3665147
  [data filename encoder]
  (let [el (.createElement js/document "a")
        data-str (js/encodeURIComponent (encoder data))]
    (doto el
      (.setAttribute "href" (str "data:text/plain;charset=utf-8,"
                                 data-str))
      (.setAttribute "download" filename))
    (aset (.-style el) "display" "none")
    (.appendChild (.-body js/document) el)
    (.click el)
    (.removeChild (.-body js/document) el)
    true))