you can now play with number of items to add

front-ui/app/stores/cartStore.js

@@ -0,0 +1,90 @@
+var AppDispatcher = require('../dispatcher/appDispatcher');
+var EventEmitter = require('events').EventEmitter;
+var CartConstants = require('../constants/cartConstants');
+var _ = require('underscore');
+
+var states = { 
+}
+
+
+var loadCart = function() {
+ 
+};
+
+var addItem = function(itemId) {
+    // TODO: push state to server side
+    var state = states[itemId] || { count: 0 };
+    state.count++;
+    states[itemId] = state;
+};
+
+var takeItemOut = function(itemId) {
+    // TODO: push state to server side
+    var state = states[itemId] || { count: 0 };
+    if (state.count > 0) {
+        state.count--;
+    }
+    states[itemId] = state;
+};
+
+
+
+
+// Extend CartStore with EventEmitter to add eventing capabilities
+var CartStore = _.extend({}, EventEmitter.prototype, {
+
+    getStateFor: function(itemId) {
+      // TODO: get from server side ?   
+      var state = states[itemId] || { count: 0 }
+      return state
+    },
+
+    // Emit Change event
+    emitChange: function() {
+        console.log("Emitting change!");
+        this.emit('change');
+    },
+
+    // Add change listener
+    addChangeListener: function(callback) {
+        this.on('change', callback);
+    },
+
+    // Remove change listener
+    removeChangeListener: function(callback) {
+        this.removeListener('change', callback);
+    }
+
+});
+
+
+// Register callback with AppDispatcher
+AppDispatcher.register(function(payload) {
+    var action = payload.action;
+    var text;
+
+    switch (action.actionType) {
+
+        case CartConstants.LOAD:
+            loadCart();
+            break;
+
+        case CartConstants.ADD_ITEM:
+            addItem(action.itemId);
+            break;
+
+        case CartConstants.TAKE_ITEM_OUT:
+            takeItemOut(action.itemId);
+            break;
+
+        default:
+            return true;
+    }
+
+    // If action was responded to, emit change event
+    CartStore.emitChange();
+    return true;
+
+});
+
+module.exports = CartStore;