rum-lifecycle-order-test.cljs

(defn log-lifecyle [component-name]
  (into {}
        (map (fn [lifecycle]
               [lifecycle (fn [state] (js/console.log component-name lifecycle) state)]))
        [:will-mount :will-unmount :did-mount :did-unmount]))

(rum/defc A < (log-lifecyle :A)
  []
  [:span "A"])

(rum/defc B < (log-lifecyle :B)
  []
  [:span "B"])

(rum/defcs LifecycleOrderTestApp
  < (rum/local true :component)
  [s]
  [:div
   (case @(:component s)
     true (A)
     false (B))
   [:div
    [:button {:on-click #(swap! (:component s) not)} "swap components"]]])

;; render A
:A :will-mount
:A :did-mount
;; replacing A with B
:B :will-mount
:A :will-unmount
:B :did-mount