It always annoys me when SPAs don't allow me to do basic things when I lose my connection.
Webstorage has excellent browser support but isn't utilised enough (http://caniuse.com/#search=webstorage)
Webstorage has excellent browser support but isn't utilised enough (http://caniuse.com/#search=webstorage)
--EDIT-- sorry @untog, I replied to the wrong comment and deleted before as you replied.
Also - these fallbacks are not exactly swappable. Its like swapping from a Database to a Filesystem as a fallback. Difficult to abstract into a single library/api.
And you still potentially leave out IE users if those are your options (depending on your IndexedDB needs).
IndexedDB to localStorage fallback might work - but again might not be an easy API abstraction.
Web SQL may be "deprecated," but it's unlikely to be dropped by Apple or Google, since so many mobile web apps depend on it. Even the mobile version of Gmail uses Web SQL.
That's isn't much of a problem with JSON.strigify and JSON.strigify.