iOS Safari Private Browsing localStorage and sessionStorage Support?

Question

I have found a few questions here on StackOverflow addressing specific functionality with iOS Safari Private Browsing and sessionStorage and localStorage. But I haven't been able to find a definitive resource denoting the support that iOS Safari has for sessionStorage and localStorage when Private Browsing.

What support is there for this or is there any specific resource from Apple denoting this functionality? The general consensus is that localStorage is not at all supported without a polyfill, does the same goes for sessionStorage?

Thank you so much!

Answer 1

Yes, same goes for sessionStorage and localStorage.

There is an excellent Gist by Paul Irish explaining the history of the issue:

https://gist.github.com/paulirish/5558557

Best solution if you only need one of them:

function isLocalStorageEnabled() {
  try {
      var mod = '__storage_test__';
      localStorage.setItem(mod, mod);
      localStorage.removeItem(mod);
      return true;
  } catch(e) {
      return false;
  }
}

Or, to make it work for both, the MDN-recommended solution is more-generic: https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API

function storageAvailable(type) {
    try {
        var storage = window[type];
        var x = '__storage_test__';
        storage.setItem(x, x);
        storage.removeItem(x);
        return true;
    }
    catch(e) {
        return false;
    }
}

Answer 2

I don't think there is any specific resource for iOS, but here's Apple's official documentation:

https://developer.apple.com/library/safari/documentation/iPhone/Conceptual/SafariJSDatabaseGuide/Name-ValueStorage/Name-ValueStorage.html

And this StackOverflow question is pretty useful as well:

QuotaExceededError: Dom exception 22: An attempt was made to add something to storage that exceeded the quota

In general, when solving for sessionStorage and localStorage, try actually developing locally with Safari on your phone with Web Inspector open. Good luck :)