I feel like using localStorage to cache stuff that could be handled by http caching is probably a mistake. I'm in the process of caching a bunch of our application in localStorage because a quirk in our client-side architecture means I need to know if something is cached before making an asynch request for content, (which you can't do with the standard http cache). That means I'm reinventing a cache invalidation scheme -- which we all know is hard, right? Plus the space allocated for localStorage is pretty small, so I have to have a way to prioritize the cache and bump out old stuff to make way for new. It's all rather convoluted.

IMHO, edge cases aside, most people shouldn't do this.