Crunker.js to ClojureScript Interop Example

crunker-interop.cljs

;; this is a ClojureScript interop example I put together for a student in
;; the Professional ClojureScript course (https://cljs.pro)

(defn fetch-and-merge-files
  "Fetches two mp3 files and merges them using the Crunker.js library.
  Returns a JavaScript Promise object."
  [file1 file2]
  (let [js-crunker (new Crunker)]
    (-> js-crunker
      (.fetchAudio file1 file2)
      (.then (fn [js-buffers]
               (.mergeAudio js-crunker js-buffers)))
      (.then (fn [js-merged]
               (.export js-crunker js-merged "audio/mp3")))
      (.then (fn [js-output]
               (.download js-crunker (oget js-output "blob"))))
      (.catch (fn [js-err]
                (.error js/console "Something went wrong:" js-err))))))

;; usage:
(-> (fetch-and-merge-files "/voice.mp3" "/background.mp3")
  (.then (fn [result-from-download])))
           ;; do something with result-from-download here...