a brief history of detecting local storage

gistfile1.md

A timeline of the last four years of detecting good old window.localStorage.

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Jan Lenhart, bless his heart contributed the first patch for support:

October 2009: 5059daa

(typeof window.localStorage != 'undefined')

Simplicifations

November 2009: 15020e7

!!window.localStorage

If cookies disabled in FF, exception. Softer detect

December 2009: 1e0ba91

!!('localStorage' in window)

If DOM storage disabled in IE, window.localStorage is present but === null.

January 2010: d8947c9

(localStorage in window) && window[localStorage] !== null

FF with dom.storage.enabled = false throws exceptions

July 2010: ef2c47

try {
  return ('localStorage' in window) && window[localstorage] !== null;
} catch(e) {
  return false;
}

more shit because of FF exceptions

December 2010: c630c39

try {
    return !!localStorage.getItem;
} catch(e) {
    return false;
}

iOS private browsing fucks everyone!!!

October 2011: 5e2fa0e

try {
    return !!localStorage.getItem('getItem');
} catch(e) {
    return false;
}

stronger full capability test for localstorage with iOS private browsing protection

October 2011: a93625c

try {
    localStorage.setItem(mod, mod);
    localStorage.removeItem(mod);
    return true;
} catch(e) {
    return false;
}

@Download The modified catch block will still return false except when the caught error happens to be "over quota error" (which is checked in four different ways), which means that the storage system is actually available, but just exhausted, and thus the (arguably) correct answer is still true

Does this gist apply equally to sessionStorage?

Yeah, in fact I think it does. Which is why that storageAvailable function accepts a type parameter. So you can use it for both localStorage and sessionStorage.

In case you want to save some bytes, instead of:

    localStorage.setItem(mod, mod);
    localStorage.removeItem(mod);

you can do this:

    localStorage.x = 1;
    delete localStorage.x;

Can anyone provide insight/their opinion on what are good uses cases for sessionStorage? https://stackoverflow.com/questions/8498357/when-should-i-use-html5-sessionstorage

@devinrhode2 I think sessionStorage is great for any data you want to share across pages and tabs for the duration of the browsing session. It will be wiped as soon as the browser closes.

@devinrhode2 I think sessionStorage is great for any data you want to share across pages and tabs for the duration of the browsing session. It will be wiped as soon as the browser closes.

Wrong.
"Opening multiple tabs/windows with the same URL creates sessionStorage for each tab/window." (source: mdn)

I have tried this !!('localStorage' in window) === true

and ('localStorage' in window)=== true 🙏 very simple