:dispatch-later now filters out nils. Fixes #455

CHANGES.md

@@ -3,6 +3,7 @@
 #### Fixed
 
   - After interceptor now runs against effect db if effect db is nil/false. [#447](https://github.com/Day8/re-frame/issues/447) 
+  - The effect handler for `:dispatch-later` will now ignore `nils`. [#455](https://github.com/Day8/re-frame/issues/455)
 
 ## 0.10.5 (2018.02.13)
 

docs/API.md

@@ -50,6 +50,14 @@ usage:
 
 Which means: in 200ms do this: `(dispatch [:event-id "param"])` and in 100ms ...
 
+Note: nil entries in the collection are ignored which means events can be added
+conditionally:
+
+```clj
+{:dispatch-later [ (when (> 3 5) {:ms 200 :dispatch [:conditioned-out]})
+                   {:ms 100 :dispatch [:another-one]}]}
+```
+
 *** 
 
 #### :dispatch

src/re_frame/fx.cljc

@@ -88,10 +88,15 @@
 ;;    {:dispatch-later [{:ms 200 :dispatch [:event-id "param"]}    ;;  in 200ms do this: (dispatch [:event-id "param"])
 ;;                      {:ms 100 :dispatch [:also :this :in :100ms]}]}
 ;;
+;; Note: nil entries in the collection are ignored which means events can be added
+;; conditionally:
+;;    {:dispatch-later [ (when (> 3 5) {:ms 200 :dispatch [:conditioned-out]})
+;;                       {:ms 100 :dispatch [:another-one]}]}
+;;
 (reg-fx
   :dispatch-later
   (fn [value]
-    (doseq [{:keys [ms dispatch] :as effect} value]
+    (doseq [{:keys [ms dispatch] :as effect} (filter nil? value)]
         (if (or (empty? dispatch) (not (number? ms)))
           (console :error "re-frame: ignoring bad :dispatch-later value:" effect)
           (set-timeout! #(router/dispatch dispatch) ms)))))