IntersectionObserver: root property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2019.

The IntersectionObserver interface's read-only root property identifies the Element or Document whose bounds are treated as the bounding box of the viewport for the element which is the observer's target.

If the root is null, then the bounds of the actual document viewport are used.

Value

A Element or Document object whose bounding box is used as the bounds of the viewport for the purposes of determining how much of the target element is visible. The intersection of this bounding rectangle, offset by any margins specified in the options passed to the IntersectionObserver() constructor, the target element's bounds, minus the bounds of every element or other object which overlaps the target element, is considered to be the visible area of the target element.

If root is null, then the owning document is used as the root, and the bounds its viewport (that is, the visible area of the document) are used as the root bounds.

Examples

This example sets the border of the intersection observer's root element to be a 2-pixel medium green line.

js
observer.root.style.border = "2px solid #44aa44";

Specifications

Specification
Intersection Observer
# dom-intersectionobserver-root

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
root

Legend

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Full support
Full support

See also