Update to accept new babel 6 module exports

lib/assets/javascripts/react_ujs_mount.js

@@ -42,6 +42,30 @@
       }
     },
 
+    // Get the constructor for a className
+    getConstructor: function(className) {
+      // Assume className is simple and can be found at top-level (window).
+      // Fallback to eval to handle cases like 'My.React.ComponentName'.
+      // Also, try to gracefully import Babel 6 style default exports
+      //
+      var constructor;
+
+      // Try to access the class globally first
+      constructor = window[className];
+
+      // If that didn't work, try eval
+      if (!constructor) {
+        constructor = eval.call(window, className);
+      }
+
+      // Lastly, if there is a default attribute try that
+      if (constructor && constructor.default) {
+        constructor = constructor.default;
+      }
+
+      return constructor;
+    },
+
     // Within `searchSelector`, find nodes which should have React components
     // inside them, and mount them with their props.
     mountComponents: function(searchSelector) {
@@ -50,10 +74,7 @@
       for (var i = 0; i < nodes.length; ++i) {
         var node = nodes[i];
         var className = node.getAttribute(window.ReactRailsUJS.CLASS_NAME_ATTR);
-
-        // Assume className is simple and can be found at top-level (window).
-        // Fallback to eval to handle cases like 'My.React.ComponentName'.
-        var constructor = window[className] || eval.call(window, className);
+        var constructor = this.getConstructor(className);
         var propsJson = node.getAttribute(window.ReactRailsUJS.PROPS_ATTR);
         var props = propsJson && JSON.parse(propsJson);