Schedule Jobs in Sequence with Promise in ClojureScript

schedule_jobs_in_sequence_in_cljs.cljs

(do
 (defn schedule-jobs-in-sequence
   "Schedules async `jobs` in sequence by using a JavaScript Promise chain."
   [jobs]
   (js/Promise.
    (fn [resolve reject]
      (let [init 42
            results (atom [])]
        (loop [promise (.resolve js/Promise init)
               [job & more] jobs]
          (if job
            (recur (.then promise (fn [result]
                                    (when (not= result init)
                                      (swap! results conj result))
                                    (job result)))
                   more)
            (-> promise
                (.then (fn [result]
                         (swap! results conj result)
                         (resolve @results)))
                (.catch (fn [error]
                          (reject error))))))))))

   (defn make-job
     [n timeout]
     (fn [v]
       (js/Promise.
        (fn [resolve reject]
          (js/setTimeout (fn []
                           (.log js/console "v:" v "job:" n)
                           (resolve n))
                         timeout)))))

   (-> (schedule-jobs-in-sequence
        (for [n (range 10)]
          (make-job n (* (rand-int n) 1000))))
       (.then (fn [results]
                (.log js/console "results:" (clj->js results))))))