The other reply (I think by the creator of HTMX) is right, HTMX is not a DSL for DOM template manipulation, but I want to address your main point about DSLs for DOM templating.
I completely see the appeal of a "it's just JS" approach that JSX and React take. But there is a massive advantage that a DSL has, the compiler can statically analyse the template and compile it in such a way that it has an understanding of what will change, what won't. This allows the compiler to make massive optimisations that JSX templates cannot do (easily). To achieve, in general, the same level of optimisation with JSX you have to code them in yourself.
Whether you go for an Angular/Vue style attribute based DSL or a Handlebars-esq DSL such as with Svelt, I don't really mind, they both have advantages and disadvantages. But what they allow you to do over JSX is enormously misunderstood by the majority of React devs.
I know, this isn't a novel concept. There was a good talk about the spectrum of abstractions and the tradeoffs of template languages vs React's approach at React Europe a couple of years ago (in fact, he goes into that this means there are some optimizations that are simply unavailable to React): https://www.youtube.com/watch?v=mVVNJKv9esE
The question isn't whether DSLs or "just JS" are more powerful, the question is which tradeoffs they represent and which tradeoffs you prefer. It seems that HTMX is primarily based in the Python ecosystem and as a former Pythonista I see the advantage of having a DSL over having to write JS, especially that the former is much narrower, which is what you want in this situation.
I completely see the appeal of a "it's just JS" approach that JSX and React take. But there is a massive advantage that a DSL has, the compiler can statically analyse the template and compile it in such a way that it has an understanding of what will change, what won't. This allows the compiler to make massive optimisations that JSX templates cannot do (easily). To achieve, in general, the same level of optimisation with JSX you have to code them in yourself.
Whether you go for an Angular/Vue style attribute based DSL or a Handlebars-esq DSL such as with Svelt, I don't really mind, they both have advantages and disadvantages. But what they allow you to do over JSX is enormously misunderstood by the majority of React devs.
There is a good overview of this in the Vue docs here: https://vuejs.org/guide/extras/rendering-mechanism.html#comp...