JSFiddle - React, Tailwind, and code Playground

JavaScript

var pageItems = {
            "stationID": "145",
            "categoryID": "-1",
            "pickupDate": "2014-04-22",
            "pickupTime": "08:00",
            "returnDate": "2014-04-23",
            "returnTime": "08:00",
            "milage": "false",
            "miles": "",
            "attributes": [{"stationID": "145","categoryID": "-1"}]
};

function setObject(key, obj) {
    localStorage.setItem(key, JSON.stringify(obj));
}

function getObject(key) {
    return JSON.parse(localStorage.getItem(key));
}

function updateItem(key, property, value)
{
    var obj = getObject(key);
    obj[property] = value;    
    setObject(key, obj);
}

//set object to sessionStorage
setObject('test', pageItems);

//update object property in sessionStorage
updateItem('test', 'attributes[0].categoryID', 65);

//get object from sessionStorage
var obj = getObject('test');

alert(JSON.stringify(obj));