first commit

src/reducers/counter.js

@@ -0,0 +1,22 @@
+import { ADD, MINUS } from '../constants/counter'
+
+const INITIAL_STATE = {
+  num: 0
+}
+
+export default function counter (state = INITIAL_STATE, action) {
+  switch (action.type) {
+    case ADD:
+      return {
+        ...state,
+        num: state.num + 1
+      }
+     case MINUS:
+       return {
+         ...state,
+         num: state.num - 1
+       }
+     default:
+       return state
+  }
+}

src/reducers/index.js

@@ -0,0 +1,6 @@
+import { combineReducers } from 'redux'
+import counter from './counter'
+
+export default combineReducers({
+  counter
+})