According to :
localStorage.setItem( key , value ); // global - not per session
sessionStorage.setItem("username", "John"); //per session
question :
where does it actually save the storage file/item ?
(multi browser answer will be much appreciated).
From a quick couple of searches on Google:
For Chrome:
http://www.techskater.com/web-stuff/accessing-google-chrome-extension-local-storage-database/
For Firefox:
https://developer.mozilla.org/en/DOM/Storage#Storage_location_and_clearing_the_data
IE:
Where in the filesystem does IE8 store values stored in localStorage?