See the quickstart from htmx.org

    <script src="https://cdn.jsdelivr.net/npm/htmx.org@2.0.8/dist/htmx.min.js"></script>
      <!-- have a button POST a click via AJAX -->
      <button hx-post="/clicked" hx-swap="outerHTML">
        Click Me
      </button>

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

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