Simple JavaScript storage (webstorage or cookie based)

storage.js

/**
 *
 * Component for utilizing local storage. It provides backup plan, if no WebStorage is available on client
 *
 *We support html5 storage, and cookie store if webStorage is not available.
 *
 *Cookies
 * Are for older browsers only. A "session" cookie (one without expiration data) is available in all windows
 * that have access to that domain until the browser is shut down. This is bad.
 * 4096 chars limit
 * 50 cookies per domain limit
 * gets posted to server and back by every response
 *
 *WebStorage (session storage)
 * A real session storage, referring to particular tab or window. Once tab is closed, that data disapperas
 * 5MB limit
 *
 *WebStorage (local storage)
 * Spans all windows on that domain
 *           *
 *Usage in code
 *To save:
 *
 *     window.AppHtml5.save("key1","val1");
 *
 *To read:
 *
 *     var jsonObj = window.AppHtml5.load("key1");
 * IMPORTANT:
 * Windows 8 / IE 10 needs workaround for exception : access is denied
 * $> icacls %userprofile%\Appdata\LocalLow /t /setintegritylevel (OI)(CI)L

 */
"use strict";

// add object STORAGE to global namespace object AppHtml5  (changes these names if you like)
//but do not pollute global scope with some name like "storage", because it might already exists
window.AppHtml5 ? window.AppHtml5.storage = { "save" : {}, "load" : {}} : window.AppHtml5 = {"storage" : { "save" : {}, "load" : {}}};

(function () {

    ////////////////////////// specific implementation

    var handler,
        webstorageHandler =  {
            _init : function(){
                return typeof (Storage) !== "undefined" ? true : false;
            },
            save : function (key, val) {
                localStorage.setItem(key, JSON.stringify(val));
            },
            load : function (key) {
                return JSON.parse(localStorage.getItem(key));
            }
        },
        cookieHandler = {
            _init : function(){
                var cookiesEnabled = (function(){
                    var id = new Date().getTime();
                    document.cookie = '_cookieprobe' + id + ';path=/';
                    return (document.cookie.indexOf(id) !== -1);
                })();
                return cookiesEnabled;
            },
            save : function (key, val) {
                var exdays = 1, exdate = new Date(), jsonStr, escapedValue;
                exdate.setDate(exdate.getDate() + exdays);
                jsonStr = JSON.stringify(val);
                escapedValue = escape(jsonStrval) + ((exdays == null) ? "" : "; expires=" + exdate.toUTCString());
                document.cookie = key + "=" + escapedValue;
            },
            load : function (key) {
                var i, x, y, unescapedValue, ARRcookies = document.cookie.split(";"), jsonObj;
                for (i = 0; i < ARRcookies.length; i++) {
                    x = ARRcookies[i].substr(0, ARRcookies[i].indexOf("="));
                    y = ARRcookies[i].substr(ARRcookies[i].indexOf("=") + 1);
                    x = x.replace(/^\s+|\s+$/g, "");
                    if (x == key) {
                        unescapedValue = unescape(y);
                        jsonObj = JSON.parse(unescapedValue);
                    }
                }
            }
    };

    //chose implementation based on what is available
    if (webstorageHandler._init())
        handler = webstorageHandler;
    else if (cookieHandler._init())
        handler = cookieHandler;
    else
        handler = {
            "save" : new function(){ alert('No support for storage')},
            "load" : new function(){ alert('No support for storage')}
        };

    //assign specific implementation to 'interface' in global namespace
    window.AppHtml5.storage.save = function(key,value){
        handler.save(key,value);
    }
    window.AppHtml5.storage.load = function(key){
        return handler.load(key);
    }


})();