That’s basically a massive hack. Every real world app will need enough js that htmx will require you to put js on front end and you’ll need to hack it together. Just like we did php+js 15 years ago.
I think HTMX lacks a sensible way to do composition and reuse on the component level, something that react/vue/solid do extremely well. Since you are basically mostly swapping html content, it gets tricky if you want to reuse partials.
That "massive hack" is supposed to be one of the core features of React.
What I've found in practice is that HTMX is extensible enough that I can write a small amount of javascript to "put a funny plug on the end of HTMX" to talk to say Leafletjs if I'm drawing maps, and want things dynamically updated.
It works quite well, and saves me an awful lot of tedious mucking about with other stuff.
But it is different this time, we are going back to HTML! /s
I've found this to not be true at all. You can do quite a lot with just HTMX. Any client-side Javascript™ you strictly need can often be done fairly minimally with Locality of Behaviour (LoB).