I'm convinced you can get most of htmx by extending standard attributes to other elements and using the standard on* attributes. htmx basically acts as a "universal/general event handler" that translates DOM events to requests and back to DOM events and modifications. It breaks down like this:

* use on* html attributes to delegate events to a universal event handler

* event handler pulls out the form attribute (if set), then pulls out action, method, target from element, or from the form if unset on the element (elements inherit these from the form they are tied to)

* if action is a URL, then initialize a fetch request using specified URL and method; if method is POST, then add a FormData payload for the specified form

* on fetch complete, the returned MIME type should match with the target attribute, which is extended to also accept a css selector:

   target=_self|_blank|_top  <=> content-type:text/html           => redirect | morph/hx-boost + push-url

   target=css selector       <=> content-type:text/html-fragment  => morph    | innerHTML

So something like:

    <a action="/url" method="post" onclick="universalHandler(event)" form="someForm" target="_self">click me</a>

I have ideas for extending beyond this, but this seems like the core of extending HTML to cover htmx semantics.