Because they are actually two distinct views: one is a details view, the other one is a form view. HTMX loads the form view and replaces the respective part of the page. But it needs to contact the backend for the form, you don't have the data model on the client like with an SPA framework, so you cannot generate the form.
HTMX is basically a JavaScript framework that makes the traditional request-response approach feels like an SPA via replacing only part(s) of the current page with the response. In this case: it loads a small form, submits it to the backend, then replaces the respective part of the page with the updated markup. The state is kept only at the backend.
With some constraints you can create a page that works with or without JS. The same endpoint can be used for serving HTML fragments for HTMX and full page for JS-disabled clients since the HTMX request can be detected by the HX-Request header.
> ...basically a JavaScript framework that makes the traditional request-response approach feels like an SPA via replacing only part(s) of the current page with the response.
Didn't that used to be called AJAX or REST or something?
Yes! HTMX is a better API on top of a XMLHttpRequest for this approach. A hypothetical next iteration of the HTML standard could make most of HTMX unnecessary. Maybe one day.
You're probably comparing htmx with client-side framework like React. Unlike those client-side ui framework, htmx is used to enhance standard html pages, such as those outputted by server-side web framework. Those frameworks typically renders detail and form page separately, and htmx can combine them into a single interactive page. For example, when you reply a comment in HN, it'll open the form as a new page, and when you submit the comment, it open another page. htmx can combine all of those pages into a single interactive page.
Should be a bit faster because it only requests a piece of html fragment which then get swapped into the dom instead of reloading the whole page again.
Yes. That's why I specified "simple page loads". If your frameworkless website is slow then the fault doesn't lie with the nature of http or the intrinsic overhead of full page loads. You've got a shitty backend framework, database or network.
It's already supported with the client-side-templates extension [1]. HTMX can fetch JSON from the backend then calls e.g. nunjucks.render() with the data.
Not at all, you can preload as many data as you wish and use vanilla or a companion JS framework like Alpine.js or HyperScript or any web-component to make the current page interactive without fetching the backend. It's a trade-off between the initial page size vs. additional network delay.
well, if you are using a hypermedia style application then you want to make a hypermedia exchange on an interaction to bring down the hypermedia representation for editing a particular resource
