Data region

A data region is a piece of UI that owns its own refresh lifecycle. It loads once on page render and then keeps itself up to date by polling, by listening for events, or by combining both. The component is just an htmx-driven container — no behavior helper needed.

Polling on a schedule

<section id="orders-summary"
         data-hx-get="/orders/summary"
         data-hx-trigger="load, every 10s"
         data-hx-swap="innerHTML">
  <p class="hc-field__message">Loading…</p>
</section>

Pieces:

data-hx-trigger="load, every 10s" — render once on page load, then again every 10 seconds.
data-hx-swap="innerHTML" — replace the container’s contents only; the container itself (with its triggers) stays put.

Always design the polled endpoint to be cheap — a fast COUNT query or a denormalized read model — and idempotent.

Whole-region self-replacement (`hx-select`)

When the endpoint can only return the full page (a server-rendered view with no fragment route), let the region cut its replacement out of that page and swap itself:

<div id="page-content"
     data-hx-get="/ops/console/outbox"
     data-hx-trigger="every 15s"
     data-hx-select="#page-content"
     data-hx-target="this"
     data-hx-swap="outerHTML">
  …
</div>

data-hx-select="#page-content" extracts the matching element from the response; data-hx-swap="outerHTML" replaces the region with it, triggers and all.
This costs a full page render per tick — prefer the fragment endpoint + innerHTML form above when you control the server, and reserve hx-select for retrofits.
With outerHTML the region’s every 15s timer restarts on each swap; with no load in the trigger the first paint is the server-rendered HTML, so there is no flash.

Event-driven refresh

Pair polling with an htmx custom event so server actions can ask the region to refresh immediately:

<section id="orders-summary"
         data-hx-get="/orders/summary"
         data-hx-trigger="load, every 30s, orders:refresh from:body"
         data-hx-swap="innerHTML">
  …
</section>

The server fires the event via HX-Trigger on any write endpoint:

HTTP/1.1 200 OK
HX-Trigger: {"hc:toast":{"message":"Created"},"orders:refresh":true}

from:body listens for the event on document.body, which is where htmx dispatches HX-Trigger events.

Reveal-driven (lazy initial load)

For data regions below the fold, defer the initial fetch until the region scrolls into view:

<section id="invoices-summary"
         data-hx-get="/invoices/summary"
         data-hx-trigger="intersect once, every 30s"
         data-hx-swap="innerHTML">
  <p class="hc-field__message">Loading when visible…</p>
</section>

intersect once fires when the element enters the viewport, once.
The subsequent every 30s only starts ticking after the first fetch.

Server response contract

The server returns only the inner content of the region:

<!-- GET /orders/summary -->
<dl class="hc-stack">
  <div>
    <dt>Open orders</dt>
    <dd>14</dd>
  </div>
  <div>
    <dt>Awaiting payment</dt>
    <dd>3</dd>
  </div>
</dl>

Return the same content for both htmx (HX-Request: true) and full-page loads. Caching can be tuned with standard Cache-Control headers; htmx respects them.

Indicators

Wrap a spinner in htmx-indicator if the polling endpoint is slow enough that flickering content matters:

<section id="status">
  <header>
    <h2>Sync status</h2>
    <span class="hc-spinner htmx-indicator" aria-hidden="true"></span>
  </header>
  <div
    data-hx-get="/status"
    data-hx-trigger="load, every 5s"
    data-hx-target="#status-body"
    data-hx-swap="innerHTML"
    data-hx-indicator="closest header .hc-spinner">
    <div id="status-body">…</div>
  </div>
</section>

Accessibility

Mark the region with aria-live="polite" when the user benefits from being told about changes (e.g. counters), or aria-live="off" if updates are noisy and decorative.
Do not move focus on each refresh. Polling that hijacks focus is hostile to keyboard users and screen readers alike.
Show an explicit empty state when the data set becomes empty so assistive tech does not encounter a silently empty section.

Progressive enhancement

Without JavaScript, the region renders its initial server-side contents and never refreshes. Render reasonable defaults inside the section instead of leaving it blank.
Without htmx, the section behaves as plain HTML.

Tips

Background tabs throttle timers. Browsers slow down polling in inactive tabs; do not rely on every 5s for real-time accuracy.
Sync points. Pair polling with SSE or WebSockets when sub-second freshness matters. The data region recipe stays the same — only the trigger changes.
Cost. Per-second polling at scale is expensive. Prefer event-driven refresh (from:body) once you have a backplane.

Live search recipe — for user-driven updates rather than time-driven.
Toast recipe — pair with HX-Trigger for cross-region notifications.