Add .parent modifier for x-intersect

[kevinruscoe]

This pull request adds support for using a parent element as the viewport for x-intersect in Alpine.js, instead of the default browser viewport. This allows elements to be observed relative to their parent container, which is useful for more complex layouts. Documentation has also been updated to explain the new .parent modifier.

Feature: Support for parent viewport in IntersectionObserver

• packages/intersect/src/index.js: Added logic to set the root option to the parent element when the parent modifier is present, enabling intersection observation relative to the parent container.

Documentation update

• packages/docs/src/en/plugins/intersect.md: Added documentation for the new .parent modifier, explaining its usage and providing an example.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a .parent modifier to the x-intersect plugin so the underlying IntersectionObserver can use the element’s parent as the observation root, and documents the new modifier.

Changes:

• Add root configuration to IntersectionObserver options when .parent is used.
• Document the new .parent modifier in the intersect plugin docs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
packages/intersect/src/index.js	Adds support for .parent by setting IntersectionObserver’s root to the element’s parent.
packages/docs/src/en/plugins/intersect.md	Documents the new .parent modifier and provides an example.

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[joshhanley]

Please update this.

[joshhanley]

@kevinruscoe thanks for the PR! Can you please add some tests? Can you also address Copilot's second concern regarding the grammar in the comment. Thanks!