throttle.cljs

(ns async-test.throttle.core
   (:require [cljs.core.async :refer [chan close!o sliding-buffer]]
            [clojure.string :as string])
  (:require-macros
    [cljs.core.async.macros :as m :refer [go alts!]]))

(def c (chan (sliding-buffer 1)))
(def loc-div (.getElementById js/document "location"))

(.addEventListener js/window "mousemove"
  (fn [e]
    (go
      (>! c [(.-x e) (.-y e)]))))

(defn timeout [ms]
  (let [c (chan)]
    (js/setTimeout (fn [] (close! c)) ms)
    c))

(defn throttle [c ms]
  (let [c' (chan)]
    (go
      (while true
        (>! c' (<! c))
        (<! (timeout ms))))
    c'))

(def throttled (throttle c 500))
 
(go
  (while true
    (let [loc (<! throttled)]
      (aset loc-div "innerHTML" (string/join ", " loc)))))

This code produces javascript errors when I move the mouse (Chrome).

It works when switching c to (def c (chan (async/sliding-buffer 1))) . I guess "pausing" doesn't quite work yet (in the CLJS implementation) otherwise (>! c [x y]) would "pause" until the event is consumed, which only happens every 500ms.

@lynaghk @thheller I made an error, I should have created a chan with a sliding-buffer, updated.