I would love to have a way to tell the browser "don't throw away the current DOM, Just apply the differences". It would work nicely in non-js page to make the experience smooth (and would probably work terribly if there was a lot of J's, of course)
This. Every major client lib out there uses some variant of vdom. If this dom diffing was natively supported, browser would request with current dom hash and server could efficiently reply with a diff that both server and client can compute to be the same new hash.
If it's forms. Client calls server with base hash + changes made by client and server replies with. Base hash + new diff to apply. The new diff includes validation changes.
