sitegeist/slipstream

Teleport any HTML tag to antoher place of the document. Mostly used for CSS and JS

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Type:neos-package

v2.3.0 2025-08-05 11:48 UTC

README

Header requirements for presentational fusion

"Quantum slipstream transcends the normal warp barrier by penetrating the quantum barrier with a focused quantum field."

The slipstream package allows defining header requirements with presentational fusion by labeling the required tags with a unique attribute. They are later deduplicated and moved to the target position. This allows defining additional the JS and CSS requirements directly with the presentational fusion components.

Authors & Sponsors

The development and the public releases of this package is generously sponsored by our employer sitegeist.

Usage

You can mark any HTML fragment to be moved to the head of the document by adding a data-slipstream attribute.

<script data-slipstream src="yourCustomScript.js"></script>
<div>your component</div>

The slipstream middleware will parse the entire page and detect all those tags. The tags are then removed from the original location and are appended to the header. Every tag is added only once, so if multiple components require the same JS, only one is added to the given location.

Alter target by tag name

By defining the data-slipstream attribute with an tag name, the target can be altered.

<script data-slipstream="//body" src="yourCustomScript.js"></script>
<div>your component</div>

Using CSS selector (id or class name) as target

If you want to target a specific element with an id or class name you can also use a selector prefixed with an # (id) or an . (class name). The string itself musst start with a letter, underscore or hyphen. No spaces are allowed. Also multiple id and classes combinations won't work, only a single class name or id works.

<dialog data-slipstream="#bar"><p>Greetings, one and all!</p></dialog>
<dialog data-slipstream=".foo"><p>Greetings, one and all!</p></dialog>

Using XPATH selector as target

<script data-slipstream="//script[@defer]" src="yourCustomScript.js"></script>

Location of the tag

To prepend the tag to the given target, you can add the data-slipstream-prepend attribute:

<script data-slipstream="//body" data-slipstream-prepend src="yourCustomScriptAfterOpenendBody.js"></script>
<script data-slipstream data-slipstream-prepend src="yourCustomScriptAfterOpenendHead.js"></script>

To place a tag before or after a specific tag, you can add the data-slipstream-before or data-slipstream-after attribute:

<script data-slipstream="//script[@defer]" data-slipstream-before src="yourCustomScript.js" defer></script>
<script data-slipstream="//script[@defer]" data-slipstream-after src="yourCustomScript.js"></script>

Debug mode

When the setting Sitegeist.Slipstream.debugMode is enabled, HTML comments are rendered to mark where tags were removed and inserted. This is enabled in Development Context by default.

Remove slipstream attributes

If the setting Sitegeist.Slipstream.removeSlipstreamAttributes is enabled, the attributes from slipstream get removed. This is disabled in Development Context by default.

Inner working and performance

The slipstream HTTP middleware will modify all responses with an active X-Slipstream: Enabled HTTP header. This header is added to Neos.Neos:Page and Sitegeist.Monocle:Preview.Page already, so this will work for Neos and Monocle right away. You will have to add the header X-Slipstream: Enabled for other controllers.

Since the response body is parsed and modified, this adds a minor performance penalty to every request. However the package is designed to work together with Flowpack.FullpageCache, which will in turn cache the whole result and mitigate the slight performance drawback.

Installation

Sitegeist.Slipstream is available via packagist run composer require sitegeist/slipstream.

We use semantic-versioning so that every breaking change will increase the major version number.

Contribution

We will gladly accept contributions. Please send us pull requests.