Both Firefox and Chrome offer users privacy features which will cause Web
Storage to be non-persistent across browser restart. For example Firefox has a
"Never remember history" option, and Chrome has a "clear cookies and other data
when I close my browser" option.
For an application developer, it would be helpful to know when such features
have been enabled, so that the application can inform the user, assist in
troubleshooting, or disable features that depend on persistent storage.
Hi.
Although I understand the reasoning, I strongly disagree with the request.
When the user open a tab in private mode, he/she knows that data will not be
stored, therefore there is no need for the webpage to reiterate that. It would
be awkward to expect each and every webpage that requires storage to warn the
user, while it should be the user agent that would properly help the user
manage his/her data.
There should be no way for a webpage to sniff if private mode is enabled: an advertiser
could block users because it wouldn't be able to set tracking cookies for instance, like
many of those sites that say "Enable cookies to continue", but in this case
applied to Storage.
Specifying that an API can change its behavior radically solely based on a user
preference goes completely against the principle of interoperability: same code
running everywhere unchanged. The last thing the user needs is the webpage
breaking because there are unexpected exceptions being thrown.
By mentioning private tabs, the same applies to other features that remove data.
So, +1 to transparency.
