Merge pull request #16 from farin/master

added state transformer (allows better immutable logging)

README.md

@@ -42,6 +42,12 @@ Receives `getState` function for  accessing current store state and `action` obj
 
 *Default: `null` (always log)*
 
+#### __transform (Function)__
+Transform state before print. Eg. convert Immutable object to plain JSON.
+
+*Default: identity function*
+
+
 ##### Examples:
 ###### log only in dev mode
 ```javascript

build/createLogger.js

@@ -24,6 +24,10 @@ function createLogger() {
         var collapsed = options.collapsed;
         var predicate = options.predicate;
         var logger = options.logger;
+        var _options$transformer = options.transformer;
+        var transformer = _options$transformer === undefined ? function (state) {
+          return state;
+        } : _options$transformer;
 
         var console = logger || window.console;
 
@@ -37,9 +41,9 @@ function createLogger() {
           return next(action);
         }
 
-        var prevState = getState();
+        var prevState = transformer(getState());
         var returnValue = next(action);
-        var nextState = getState();
+        var nextState = transformer(getState());
         var time = new Date();
         var actionType = String(action.type);
         var message = 'action ' + actionType + ' @ ' + time.getHours() + ':' + time.getMinutes() + ':' + time.getSeconds();

src/createLogger.js

@@ -10,7 +10,7 @@
 
 function createLogger(options = {}) {
   return ({ getState }) => (next) => (action) => {
-    const { level, collapsed, predicate, logger } = options;
+    const { level, collapsed, predicate, logger, transformer = state => state} = options;
     const console = logger || window.console;
 
     // exit if console undefined
@@ -23,9 +23,9 @@ function createLogger(options = {}) {
       return next(action);
     }
 
-    const prevState = getState();
+    const prevState = transformer(getState());
     const returnValue = next(action);
-    const nextState = getState();
+    const nextState = transformer(getState());
     const time = new Date();
     const actionType = String(action.type);
     const message = `action ${actionType} @ ${time.getHours()}:${time.getMinutes()}:${time.getSeconds()}`;