LocalStorage JSON Handler

localstorage-json.js

/*
 * LocalStorageFactory 
 * adds support for JSON objects in LocalStorage
 *
 * @author jvarandas
 */
(function(global) {
    var _cache = {}, _ls = {}, ls;

    // if localStorage is not available, create a localStorage stub  
    if (typeof localStorage === 'undefined') {       
        ls = {
            setItem: function(key, value) {
              _ls[key] = value;
            },
            getItem: function(key) {
              return _ls[key];
            }            
        }
    } else {
        ls = localStorage;
    }

    /**
     * Append key/value pair into LocalStorage object
     */
    function fnAppender(key, value) {
        this.data[key] = value;    

        return this.data;
    }

    /**
     * Updates LocalStorage with the latest version
     */
    function fnSetter() {
        ls.setItem(this.key, JSON.stringify(this.data));
    }
  
    /**
     * LocalStorageFactory
     * main-init
     */
    function fnFactory(key) {
        
        // we don't want multiple instances of our localStorage object
        if (_cache[key]) return _cache[key];
        
        // multi-thread issue 
        var jsonString = ls.getItem(key);
        _cache[key] = jsonString ? JSON.parse(jsonString) : {};
        var o = _cache[key];
        // end of multi-thread issue 
        
        // setup append/set functions in this object
        var g = {
            "key": key,
            "data": o
        };
        o["set"] = fnSetter.bind(g);
        o["append"] = fnAppender.bind(g);
        
        return o;
    }

    // export LocalStorageFactory to window/global
    global["LocalStorageFactory"] = fnFactory;

})(window);