store json array and sync to localstorage

Hi i am new for sencha touch. I need to sync online data to offline localstorage. Please see my json result.The json result is store in hierarchy format and getting from server

Json result

Code:

items": [        "loyaltyMasterId": "6",
        "loyaltyCardId": "23",
        "totalPoint": "0.00",
        "lastVisited": "2013-10-23 13:35:17.062",
        "pushNotification": "Y",
        "blueDisplay": "Y",
        "loyaltyCardName": "Jusco",
        "headerCss1": "",
        "headerCss2": "",
        "borderLcss": "",
        "borderRcss": "",
        "borderScss": "",
        items": [
                "loyaltyMasterId": "7",
                "loyaltyCardId": "23",
                "totalPoint": "0.00",
                "lastVisited": "2013-10-23 13:35:17.062",
                "pushNotification": "Y",
                "blueDisplay": "Y",
                "loyaltyCardName": "Jusco",
                "headerCss1": "",
                "headerCss2": "",
                "borderLcss": "",
                "borderRcss": "",
                "borderScss": "",
        
        ]
],

ModelOffline js

Code:

Ext.define('blackbutton.model.Blue.BlueList_Off9', { //Oyster create 17-Sept-2013  for store localstorage    extend: 'Ext.data.Model',
     requires: ['Ext.ux.Global.GlobalVariable'],
    config: {
        idProperty: 'loyaltyMasterId',
        identifier: 'uuid',
        fields: [
                 { name: 'loyaltyMasterId' },
                 { name: 'loyaltyCardId' },
                 { name: 'totalPoint' },
                 { name: 'lastVisited' },
                 { name: 'loyaltyCardName' },
                 { name: 'headerCss1' },
                 { name: 'headerCss2' },
                 { name: 'borderLcss' },
                 { name: 'borderRcss' },
                 { name: 'borderScss' },
                 { name: 'headerImage1' },
                 { name: 'headerImage2' },
                 { name: 'contentImage1' },
                 { name: 'contentImage2' },
                 { name: 'bottomImage1' },
                 { name: 'bottomImage2' },
                 { name: 'bodyCss1' },
                 { name: 'bodyCss2' },
                 { name: 'contentCss1' },
                 { name: 'contentCss2' },
                 { name: 'bottomCss1' },
                 { name: 'bottomCss2' },
                 { name: 'designType' },
                 { name: 'couponType' },
                  { name: 'pushNotification', type: 'string' },
                  { name: 'blueDisplay', type: 'string' },
                  { name: 'result',type: 'string' },
                 { name: 'sessionId' },
                 { name: 'deviceId' },
                 { name: 'SN' }
        ],


        proxy: {
            type: 'localstorage',
            id  : 'blueListoff9',
            noCache: false, // get rid of the '_dc' url parameter
            
            extraParams: {
                sessionId: "1",
            },
        }
    }
});

StoreOffline

Code:

Ext.define('blackbutton.store.Blue.BlueList_Off9', {    //extend: 'Ext.data.TreeStore',
     extend: 'Ext.data.Store',
    requires: [
       'blackbutton.model.Blue.BlueList'
    ],
    config: {            
        //defaultRootProperty: 'items',
        model: 'blackbutton.model.Blue.BlueList_Off9',
        storeId : 'blueListStore_Off9',
         autoLoad: true,
         clearOnPageLoad: true,
        


    }
});

How i store to localstorage

Code:

  markerStore.getProxy().setTimeout(120000);            markerStore.load(function(records, operation, successful) {
              
                if(successful) {
                    var responseText = operation.getResponse().responseText;
                    var objresponseText = JSON.stringify(responseText);
                    markerStoreLocalStorage.add(objresponseText);
                    markerStoreLocalStorage.sync();
                       markerStoreLocalStorage.load();


//                    
                    
                }
            });

console.of objresponseText

Code:

"{\"items\":[{\"loyaltyMasterId\":\"6\",\"loyaltyCardId\":\"23\",\"totalPoint\":\"0.00\",\"lastVisited\":\"2013-10-23 13:35:17.062\",\"pushNotification\":\"Y\",\"blueDisplay\":\"Y\",\"loyaltyCardName\":\"Jusco\",\"headerCss1\":\"\",\"headerCss2\":\"\",\"borderLcss\":\"\",\"borderRcss\":\"\",\"borderScss\":\"\",\"headerImage1\":\"iVBORw0KGgoAAAANSUhEUgAAADAAAAAXCAYAAABNq8wJAAAABHNCSVQICAgIfAhkiAAAAAlwSFlz\\r\\nAAALEgAACxIB0t1+\\/AAAAMJ0RVh0U29mdHdhcmUAVGhpcyBkb2N1bWVudCBjb250YWlucyBubyB ....
 

My loclstorage is getting empty. Any solution? Thanks