Check these out, one of it might help
http://www.w3.org/TR/IndexedDB/ – Indexed DB
http://www.w3.org/TR/webdatabase/ – Web Sql
http://www.w3.org/TR/webstorage/ – localStorage
You can as well try out a JavaScript Database here
http://www.taffydb.com/ still trying it out myself, hope this helps.
solved How to register a user using only javascript/ajax or jquery [closed]