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HTMX Overview

When to Use

You're building interactive Drupal features that update page regions without full page reloads, and you want a simpler approach than traditional AJAX with JSON commands.

What HTMX Is

HTMX extends HTML with attributes that enable dynamic content updates without extensive JavaScript. Elements issue HTTP requests and swap content directly in the DOM using declarative markup:

<button data-hx-get="/contacts/1" data-hx-target="#contact-ui">
  Fetch Contact
</button>

Reference: Core implementation at /core/lib/Drupal/Core/Htmx/Htmx.php — comprehensive API for all HTMX attributes and headers.

Why Drupal Adopted HTMX

Drupal 11.3 introduced native HTMX support as a simpler alternative to traditional AJAX.

Key Benefits: - Declarative approach: HTML attributes replace imperative JavaScript - Smaller footprint: Reduced JavaScript compared to traditional AJAX framework - Progressive enhancement: Forms/links work without JavaScript - Hypermedia-driven: Aligns with web platform patterns - Seamless integration: Works with Drupal's render system and behaviors

Reference: Change record "Ajax subsystem now includes HTMX" published September 10, 2025 (Drupal 11.3.0).

Common Mistakes

  • Assuming HTMX replaces all AJAX — Traditional AJAX still needed for complex command sequences and contrib module compatibility
  • Not using _htmx_route: TRUE or onlyMainContent() — Results in full page renders instead of minimal responses
  • Forgetting progressive enhancement — Always provide non-JavaScript fallback for forms and links
  • Using HTMX for heavy client-side processing — HTMX is server-driven; complex JavaScript logic belongs in traditional patterns

See Also