htmx supports using morphdom for swapping with the morphdom-swap extension
agree 100% w/ @Craig's characterization of htmx as lower level than unpoly: it's an extension of HTML rather than a full framework (with, for example, a notion of layers). That can be good or bad, depending on your needs. Unpoly is a wonderful library that follows the same general html-oriented approach, but provides a lot more infrastructure baked into the core. I think either one (or, hotwire, for that matter, which is even higher level than unpoly) is a great choice for html-oriented development.
I obviously prefer the lower-level "improve on HTML" approach, but they all have plusses and minuses. I'm (all to) happy to chat about htmx either here, on the htmx discord, or anywhere else.
-t.totallyNotAnHtmxShill