See the quickstart from htmx.org

    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/htmx.min.js"></script>
      <!-- have a button POST a click via AJAX -->
      <button hx-post="/clicked" hx-swap="outerHTML">
        Click Me
      </button>

When the user clicks the button the browser will take the result of the request to `/clicked` and swap the whole button dom node for whatever the server sent.

As a dev you get to write HTML, and need to learn about some new tag attributes.

Your browser is still running js.