Load React, ReactDOM etc on init

That should make error messages easier to see.

src/reagent/core.cljs

@@ -13,8 +13,7 @@
 
 (def is-client util/is-client)
 
-(defn react []
-  util/react)
+(def react util/react)
 
 (defn create-element
   "Create a native React element, by calling React.createElement directly.
@@ -34,13 +33,13 @@ which is equivalent to
    (create-element type nil))
   ([type props]
    (assert (not (map? props)))
-   ($ (react) createElement type props))
+   ($ react createElement type props))
   ([type props child]
    (assert (not (map? props)))
-   ($ (react) createElement type props child))
+   ($ react createElement type props child))
   ([type props child & children]
    (assert (not (map? props)))
-   (apply ($ (react) :createElement) type props child children)))
+   (apply ($ react :createElement) type props child children)))
 
 (defn as-element
   "Turns a vector of Hiccup syntax into a React element. Returns form unchanged if it is not a vector."

src/reagent/dom.cljs

@@ -5,45 +5,38 @@
             [reagent.debug :refer-macros [dbg]]
             [reagent.interop :refer-macros [$ $!]]))
 
-(defonce ^:private react-dom nil)
+(defonce dom (or (and (exists? js/ReactDOM)
+                      js/ReactDOM)
+                 (and (exists? js/require)
+                      (js/require "react-dom"))))
+
+(assert dom "Could not find ReactDOM")
 
 (defonce ^:private roots (atom {}))
 
-(defn- dom []
-  (if-some [r react-dom]
-    r
-    (do
-      (set! react-dom
-            (or (and (exists? js/ReactDOM)
-                     js/ReactDOM)
-                (and (exists? js/require)
-                     (js/require "react-dom"))))
-      (assert react-dom "Could not find ReactDOM")
-      react-dom)))
-
 (defn- unmount-comp [container]
   (swap! roots dissoc container)
-  ($ (dom) unmountComponentAtNode container))
+  ($ dom unmountComponentAtNode container))
 
 (defn- render-comp [comp container callback]
   (binding [util/*always-update* true]
-    (->> ($ (dom) render (comp) container
-             (fn []
-               (binding [util/*always-update* false]
-                 (swap! roots assoc container [comp container])
-                 (if (some? callback)
-                   (callback))))))))
+    (->> ($ dom render (comp) container
+            (fn []
+              (binding [util/*always-update* false]
+                (swap! roots assoc container [comp container])
+                (if (some? callback)
+                  (callback))))))))
 
 (defn- re-render-component [comp container]
   (render-comp comp container nil))
 
 (defn render
   "Render a Reagent component into the DOM. The first argument may be
-either a vector (using Reagent's Hiccup syntax), or a React element. The second argument should be a DOM node.
+  either a vector (using Reagent's Hiccup syntax), or a React element. The second argument should be a DOM node.
 
-Optionally takes a callback that is called when the component is in place.
+  Optionally takes a callback that is called when the component is in place.
 
-Returns the mounted component instance."
+  Returns the mounted component instance."
   ([comp container]
    (render comp container nil))
   ([comp container callback]
@@ -57,7 +50,7 @@ Returns the mounted component instance."
 (defn dom-node
   "Returns the root DOM node of a mounted component."
   [this]
-  ($ (dom) findDOMNode this))
+  ($ dom findDOMNode this))
 
 (set! tmpl/find-dom-node dom-node)
 

src/reagent/dom/server.cljs

@@ -4,28 +4,21 @@
             [reagent.impl.template :as tmpl]
             [reagent.interop :refer-macros [$ $!]]))
 
-(defonce ^:private react-server nil)
+(defonce server (or (and (exists? js/ReactDOMServer)
+                         js/ReactDOMServer)
+                    (and (exists? js/require)
+                         (js/require "react-dom/server"))))
 
-(defn- server []
-  (if-some [r react-server]
-    r
-    (do
-      (set! react-server
-            (or (and (exists? js/ReactDOMServer)
-                     js/ReactDOMServer)
-                (and (exists? js/require)
-                     (js/require "react-dom/server"))))
-      (assert react-server "Could not find ReactDOMServer")
-      react-server)))
+(assert server "Could not find ReactDOMServer")
 
 (defn render-to-string
   "Turns a component into an HTML string."
   [component]
   (binding [util/*non-reactive* true]
-    ($ (server) renderToString (tmpl/as-element component))))
+    ($ server renderToString (tmpl/as-element component))))
 
 (defn render-to-static-markup
   "Turns a component into an HTML string, without data-react-id attributes, etc."
   [component]
   (binding [util/*non-reactive* true]
-    ($ (server) renderToStaticMarkup (tmpl/as-element component))))
+    ($ server renderToStaticMarkup (tmpl/as-element component))))