It's enough to read the context of the discussion, don't you think?
Original complaint: "it's describing a "whole other language" they call Hyperscript"
Response: hyperscript is a completely separate technology. htmx generalizes hypermedia controls, that's pretty much it, and it can be used with any scripting tool you'd like
My response:
In reality [1] htmx defines its own non-optional DSL that you have to use.
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I will add that as with any organically grown nice-to-have utility DSLs it's quite haphazard (it's hyperscript-like in one place, js-like in another place, both in some other places etc.). But that's the nature of such ad-hoc informally specified DSLs
[1] which can be easily verified by just visiting https://htmx.org
The only place where it talks about anything else is a small section on scripting with a link out to a huge meandering essay with small examples lost in all the philosophical discussions.
Edit: Don't forget also that this is entirely non-optional because if you use htmx, you will load the full support for it whether you use it or not