HTML5 localStorage size limit for subdomains
HTML5's localStorage databases are usually size-limited — standard sizes are 5 or 10 MB per domain. Can these limits be circumvented by subdomains (e.g. example.com, hack1.example.com and hack2.example.com all have their own 5 MB databases)? And is there anything in the standard that specifies whether parent domains can access their children's databases? I can't find anything, and I can see arguments for doing it either way, but it seems like there has to be some standard model.
Answer
From http://dev.w3.org/html5/webstorage/#disk-space
A mostly arbitrary limit of five megabytes per origin is recommended. Implementation feedback is welcome and will be used to update this suggestion in the future.
It also mentions that :
User agents should guard against sites storing data under the origins other affiliated sites, e.g. storing up to the limit in a1.example.com, a2.example.com, a3.example.com, etc, circumventing the main example.com storage limit.