hx-boost

Syntax

Override target, swap, and history behavior with their corresponding attributes. Boosted links always use click.

Boost several links from a parent:

<div hx-boost:inherited="true">
  <a href="/page1">Page 1</a>
  <a href="/page2">Page 2</a>
</div>

Each link sends GET, pushes its URL, and swaps the response into <body> with outerSync.

outerSync replaces body children and syncs body attributes without replacing the <body> element.

Boost a form directly:

<form hx-boost="true" action="/example" method="post">
  <input name="email" type="email">
  <button>Submit</button>
</form>

The form sends POST and swaps the response into <body> without pushing a URL. Add hx-push-url to create a history entry.

Advanced Syntax

You can configure boost behavior using a config string that sets swap, target, and other options directly on the hx-boost attribute. Use hx-boost:inherited to pass that config down to all boosted descendants.

<!-- outerSync + select + target: pull #main from the full-page response and swap it in place,
     syncing #main's attributes (class, data-*, etc.) at the same time -->
<body hx-boost:inherited="swap:outerSync select:#main target:#main">
  <nav>
    <!-- These links inherit the boost config above -->
    <a href="/page1">Go To Page 1</a>
    <a href="/page2">Go To Page 2</a>

    <!-- Nested override: descendants of this div use a different boost config -->
    <div hx-boost:inherited="swap:'innerHTML strip' target:#sidebar">
      <a href="/sidebar">Sidebar</a>

      <!-- Per-element override: this link uses its own config, ignoring all inherited -->
      <a href="/modal" hx-boost="swap:beforeend target:#modals">Open Modal</a>

      <!-- Disable boost for this link -->
      <a href="/external" hx-boost="false">External</a>
    </div>
  </nav>

  <!-- Non-boosted htmx elements are unaffected by hx-boost:inherited -->
  <div hx-get="/data" hx-trigger="load">Loading...</div>

  <div id="main"></div>
  <div id="sidebar"></div>
  <div id="modals"></div>
</body>

The key advantage is that boost config only applies to boosted elements (links and forms), unlike inherited hx-* attributes which would affect all descendant htmx elements.

Priority Order

Boost config overrides explicit hx-* attributes on the element:

1. Boost config (highest priority)
2. Explicit hx-* attributes
3. Default values (lowest priority)

This allows you to:

• Set base defaults with hx-target, hx-swap on elements
• Override them with hx-boost:inherited at any level
• Use hx-boost="true" or hx-boost="false" to enable/disable

Supported modifiers:

• swap:STYLE - Swap strategy (outerSync, innerHTML, outerHTML, etc.)
• target:SELECTOR - Target element selector
• select:SELECTOR - Content selection from response (works with outerSync; use innerHTML strip instead of innerHTML + select when targeting a non-body element)

Anchor Boosting

Anchors are boosted when they navigate to the same origin in the current window:

<a href="/example">Same-origin link</a>
<a href="/example" target="_self">Same-origin link targeting this window</a>

These anchors are not boosted:

<a href="https://other-domain.com/example">Different origin</a>
<a href="#section">Local anchor</a>
<a href="/report.pdf" download>Browser download</a>
<a href="/example" target="_blank">New window or tab</a>

Notes

• All requests are done via AJAX, so keep that in mind when doing things like redirects
• To find out if the request results from a boosted anchor or form, look for HX-Boosted in the request header
• Selectively disable boost on child elements with hx-boost="false"
• Disable the replacement of elements via boost, and their children, with hx-preserve="true"