debounce.cljs

(require '[clojure.core.async :as a]
         '[kitchen-async.promise :as p]
         '[kitchen-async.promise.from-channel])

(comment

  ;; cf. https://gist.github.com/swannodette/5888989

  (defn debounce
    ([c ms] (debounce (a/chan) c ms))
    ([c' c ms]
     (a/go
       (loop [start nil loc (a/<! c)]
         (if (nil? start)
           (do
             (>! c' loc)
             (recur (js/Date.) nil))
           (let [loc (a/<! c)]
             (if (>= (- (js/Date.) start) ms)
               (recur nil loc)
               (recur (js/Date.) loc))))))
     c'))

  )

;; Using kitchen-async, this can also be written as follows:

(defn debounce
  ([c ms] (debounce (a/chan) c ms))
  ([c' c ms]
   (p/loop [start nil loc c]
     (if (nil? start)
       (do
         (a/put! c' loc)
         (p/recur (js/Date.) nil))
       (p/let [loc c]
         (if (>= (- (js/Date.) start) ms)
           (p/recur nil loc)
           (p/recur (js/Date.) loc)))))
   c'))