Web/API/IntersectionObserver/root

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.

Syntax

var root = intersectionObserver.root;

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.

Example

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

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

Specifications

Specification	Status	Comment
Intersection ObserverThe definition of 'IntersectionObserver' in that specification.	Working Draft	Initial definition

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`root` Experimental'	Chrome Full support 51	Edge Full support 15	Firefox Full support 55 Full support 55 No support 53 — 55 Disabled' Disabled' From version 53 until version 55 (exclusive): this feature is behind the `dom.IntersectionObserver.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support Yes	Safari Full support 12.1	WebView Android Full support 51	Chrome Android Full support 51	Firefox Android ?	Opera Android ?	Safari iOS Full support 12.2	Samsung Internet Android Full support 5.0

Legend

Full support: Full support
No support: No support
Compatibility unknown: Compatibility unknown
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
User must explicitly enable this feature.': User must explicitly enable this feature.