Fake localStorage. Useful for Safari Private Browsing and browsers that don't implement localStorage.

fakeLocalStorage.js

// Fake localStorage implementation. 
// Mimics localStorage, including events. 
// It will work just like localStorage, except for the persistant storage part. 

var fakeLocalStorage = function() {
  var fakeLocalStorage = {};
  var storage; 
  
  // If Storage exists we modify it to write to our fakeLocalStorage object instead. 
  // If Storage does not exist we create an empty object. 
  if (window.Storage && window.localStorage) {
    storage = window.Storage.prototype; 
  } else {
    // We don't bother implementing a fake Storage object
    window.localStorage = {}; 
    storage = window.localStorage; 
  }
  
  // For older IE
  if (!window.location.origin) {
    window.location.origin = window.location.protocol + "//" + window.location.hostname + (window.location.port ? ':' + window.location.port: '');
  }

  var dispatchStorageEvent = function(key, newValue) {
    var oldValue = (key == null) ? null : storage.getItem(key); // `==` to match both null and undefined
    var url = location.href.substr(location.origin.length);
    var storageEvent = document.createEvent('StorageEvent'); // For IE, http://stackoverflow.com/a/25514935/1214183

    storageEvent.initStorageEvent('storage', false, false, key, oldValue, newValue, url, null);
    window.dispatchEvent(storageEvent);
  };

  storage.key = function(i) {
    var key = Object.keys(fakeLocalStorage)[i];
    return typeof key === 'string' ? key : null;
  };

  storage.getItem = function(key) {
    return typeof fakeLocalStorage[key] === 'string' ? fakeLocalStorage[key] : null;
  };

  storage.setItem = function(key, value) {
    dispatchStorageEvent(key, value);
    fakeLocalStorage[key] = String(value);
  };

  storage.removeItem = function(key) {
    dispatchStorageEvent(key, null);
    delete fakeLocalStorage[key];
  };

  storage.clear = function() {
    dispatchStorageEvent(null, null);
    fakeLocalStorage = {};
  };
};

// Example of how to use it
if (typeof window.localStorage === 'object') {
  // Safari will throw a fit if we try to use localStorage.setItem in private browsing mode. 
  try {
    localStorage.setItem('localStorageTest', 1);
    localStorage.removeItem('localStorageTest');
  } catch (e) {
    fakeLocalStorage();
  }
} else {
  // Use fake localStorage for any browser that does not support it.
  fakeLocalStorage();
}

LICENSE

The MIT License (MIT)

Copyright (c) 2015 Textalk

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.

Licensed under the MIT license, copyright Textalk

Thanks for that !

I cant implement it, my website doesnt fully load on private browsing

thx for this script! it helps me a lot.
how to modify this script to do the same with sessionStorage?
is this a good way to do such like:
window.sessionStorage = window.localStorage;

this will not survive the reload, so what's the point? if your site does not reload, it should not need local storage - in fact, something like this gist should have been used by default

@zmaksalar, this is for when you want to have a central API the rest of your application can use, across browsers. The point is your app can use localStorage where available, and then store information temporarily when it's not, but you don't have to "think" about the Safari edge-case.