fix: synchronize global 'config' var with the reducer's state

react/features/base/config/index.js

@@ -2,4 +2,5 @@ export * from './actions';
 export * from './actionTypes';
 export * from './functions';
 
+import './middleware';
 import './reducer';

react/features/base/config/middleware.js

@@ -0,0 +1,52 @@
+// @flow
+
+import { MiddlewareRegistry } from '../redux';
+
+import { SET_CONFIG } from './actionTypes';
+
+/**
+ * The middleware of the feature {@code base/config}.
+ *
+ * @param {Store} store - The redux store.
+ * @private
+ * @returns {Function}
+ */
+MiddlewareRegistry.register(store => next => action => {
+    switch (action.type) {
+    case SET_CONFIG:
+        return _setConfig(store, next, action);
+    }
+
+    return next(action);
+});
+
+/**
+ * Notifies the feature {@code base/config} that the {@link SET_CONFIG} redux
+ * action is being {@code dispatch}ed in a specific redux store.
+ *
+ * @param {Store} store - The redux store in which the specified {@code action}
+ * is being dispatched.
+ * @param {Dispatch} next - The redux {@code dispatch} function to dispatch the
+ * specified {@code action} in the specified {@code store}.
+ * @param {Action} action - The redux action which is being {@code dispatch}ed
+ * in the specified {@code store}.
+ * @private
+ * @returns {*} The return value of {@code next(action)}.
+ */
+function _setConfig({ getState }, next, action) {
+    // The reducer is doing some alterations to the config passed in the action,
+    // so make sure it's the final state by waiting for the action to be
+    // reduced.
+    const result = next(action);
+
+    // FIXME On Web we rely on the global 'config' variable which gets altered
+    // multiple times, before it makes it to the reducer. At some point it may
+    // not be the global variable which is being modified anymore due to
+    // different merge methods being used along the way. The global variable
+    // must be synchronized with the final state resolved by the reducer.
+    if (typeof window.config !== 'undefined') {
+        window.config = getState()['features/base/config'];
+    }
+
+    return result;
+}