There are ways to cache responses defined in HTTP standard since first version. No fancy HTML5 features is required for that. (And if you meant using hashes to

There are ways to cache responses defined in HTTP standard since first version. No fancy HTML5 features is required for that. (And if you meant using hashes to use cache for resources from different domains - there probably will be many misses because every website can use different library versions, they can compress or bundle libraries etc).