storing assets clientside permanently (or extended period of time)

Question

Consider a HTML5 game, rather heavy on the assets, is it possible to somehow provide the user with an option to store the assets locally, in order to avoid loading all those assets again each time he loads the game?

Answer 1

Yes, there are several options:

• Web Storage (localStorage/sessionStorage) can be used to store strings (or stringified objects). It has limited storage capacity but is very easy to use.

• Indexed DB is a light database which allow you to store any kind of objects incl. BLOBs. It has a default limit (typically 5 mb) but has an interface that allows you to request more storage space.

• Web SQL is also a database, although deprecated it has still good support in for example Safari (which do not support Indexed DB) and works by executing short SQL queries.

• File system API is in the works but not widely supported (only Chrome for now). As with Indexed DB you can request larger storage space, in fact very large in this case. It's a pseudo file system which allow you store any kind of data.

• And finally there is the option of application cache using manifest files and off-line storage. You can download the assets and define them using manifest files which makes them available to the app without having to consult server.

There are legacy mechanisms such as UserData in IE and of course cookies which probably has very limited use here and has it downsides such as being sent forth and back between server for every page request.

In general I would recommend web storage if the amount of data is low, or Indexed DB (Web SQL in browsers which do not support Indexed DB) for larger data. File system is cool but has little support as of yet.

Note: There is no guarantee the data will be stored on client permanently (user can choose directly or indirectly to clear stored data) so this must be taken into consideration.