Buffer messages while ws disconnected, replay later

src/nextjournal/clerk/render/editor.cljs

@@ -221,7 +221,7 @@
  {:key "Escape"
  :run #(reset! !show-docstring? false)}]))]))
  @!container-el))]
- (goog.events/listenOnce js/window "clerk.wsopen" #(on-eval view) false)
+ (on-eval view)
  #(.destroy view))))
  (code/use-dark-mode !view)
  [:<>

src/nextjournal/clerk/sci_env.cljs

@@ -201,15 +201,26 @@
 (defn reconnect-timeout [failed-connection-attempts]
  (get [0 0 100 500 5000] failed-connection-attempts 10000))
 
+(def !ws-connection
+ (atom {:outbox (.-EMPTY cljs.core.PersistentQueue) :connected? false}))
+
+(defn ws-connected? [] (:connected? @!ws-connection))
+(defn flush-ws-outbox []
+ (let [out (:outbox @!ws-connection)]
+ (swap! !ws-connection assoc :outbox (.-EMPTY cljs.core.PersistentQueue))
+ out))
+
 (defn ^:export connect [ws-url]
  (when (::failed-attempts @render/!doc)
  (swap! render/!doc assoc ::connection-status "Reconnecting…"))
  (let [ws (js/WebSocket. ws-url)]
  (set! (.-onmessage ws) onmessage)
  (set! (.-onopen ws) (fn [e]
+ (swap! !ws-connection assoc :connected? true)
  (swap! render/!doc dissoc ::connection-status ::failed-attempts)
- (.dispatchEvent js/window (new js/Event "clerk.wsopen"))))
+ (doseq [msg (flush-ws-outbox)] (.send ws msg))))
  (set! (.-onclose ws) (fn [e]
+ (swap! !ws-connection assoc :connected? false)
  (let [timeout (reconnect-timeout (::failed-attempts @render/!doc 0))]
  (swap! render/!doc
  (fn [doc]
@@ -220,7 +231,11 @@
  (update ::failed-attempts (fnil inc 0)))))
  (js/setTimeout #(connect ws-url) timeout))))
  (set! (.-clerk_ws ^js goog/global) ws)
- (set! (.-ws_send ^js goog/global) (fn [msg] (.send ws msg)))))
+ (set! (.-ws_send ^js goog/global)
+ (fn [msg]
+ (if (ws-connected?)
+ (.send ws msg)
+ (swap! !ws-connection update :outbox conj msg))))))
 
 (sci.ctx-store/reset-ctx! (sci/init initial-sci-opts))