jquery.storage.js

/* Copyright (c) 2010 Marcus Westin
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/

(function ($) {
    var storage = function (name) {
        var api = {},
            win = window,
            doc = win.document,
            localStorageName = name,
            globalStorageName = 'globalStorage',
            storage;

        api.disabled = false;
        api.set = function (key, value) { };
        api.get = function (key) { };
        api.remove = function (key) { };
        api.clear = function () { };
        api.transact = function (key, transactionFn) {
            var val = api.get(key);
            if (typeof val == 'undefined') {
                val = {};
            }
            transactionFn(val);
            api.set(key, val);
        };

        api.serialize = function (value) {
            return JSON.stringify(value);
        };
        api.deserialize = function (value) {
            if (typeof value != 'string') { return undefined; }
            return JSON.parse(value);
        };

        // Functions to encapsulate questionable FireFox 3.6.13 behavior
        // when about.config::dom.storage.enabled === false
        // See https://github.com/marcuswestin/store.js/issues#issue/13
        function isLocalStorageNameSupported() {
            try {
                return (localStorageName in win && win[localStorageName]);
            }
            catch (err) {
                return false;
            }
        }

        function isGlobalStorageNameSupported() {
            try {
                return (globalStorageName in win && win[globalStorageName] && win[globalStorageName][win.location.hostname]);
            }
            catch (err) {
                return false;
            }
        }

        if (isLocalStorageNameSupported()) {
            storage = win[localStorageName];
            api.set = function (key, val) { storage.setItem(key, api.serialize(val)); };
            api.get = function (key) { return api.deserialize(storage.getItem(key)); };
            api.remove = function (key) { storage.removeItem(key); };
            api.clear = function () { storage.clear(); };

        } else if (isGlobalStorageNameSupported()) {
            storage = win[globalStorageName][win.location.hostname];
            api.set = function (key, val) { storage[key] = api.serialize(val); };
            api.get = function (key) { return api.deserialize(storage[key] && storage[key].value); };
            api.remove = function (key) { delete storage[key]; };
            api.clear = function () { for (var key in storage) { delete storage[key]; } };

        } else if (doc.documentElement.addBehavior) {
            var storage = doc.createElement('div');
            function withIEStorage(storeFunction) {
                return function () {
                    var args = Array.prototype.slice.call(arguments, 0);
                    args.unshift(storage);
                    // See http://msdn.microsoft.com/en-us/library/ms531081(v=VS.85).aspx
                    // and http://msdn.microsoft.com/en-us/library/ms531424(v=VS.85).aspx
                    doc.body.appendChild(storage);
                    storage.addBehavior('#default#userData');
                    storage.load(localStorageName);
                    var result = storeFunction.apply(api, args);
                    doc.body.removeChild(storage);
                    return result;
                };
            }
            api.set = withIEStorage(function (storage, key, val) {
                storage.setAttribute(key, api.serialize(val));
                storage.save(localStorageName);
            });
            api.get = withIEStorage(function (storage, key) {
                return api.deserialize(storage.getAttribute(key));
            });
            api.remove = withIEStorage(function (storage, key) {
                storage.removeAttribute(key);
                storage.save(localStorageName);
            });
            api.clear = withIEStorage(function (storage) {
                var attributes = storage.XMLDocument.documentElement.attributes;
                storage.load(localStorageName);
                for (var i = 0, attr; attr = attributes[i]; i++) {
                    storage.removeAttribute(attr.name);
                }
                storage.save(localStorageName);
            });
        } else {
            api.disabled = true;
        }

        return api;
    };

    // Set jQuery variables.
    $.localStorage = storage("localStorage");
    $.sessionStorage = storage("sessionStorage");
}(jQuery));