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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The IntersectionObserver method observe() adds an element to the set of target elements being watched by the IntersectionObserver. One observer has one set of thresholds and one root, but can watch multiple target elements for visibility changes in keeping with those. To stop observing the element, call IntersectionObserver.unobserve().

When the visibility of the specified element crosses over one of the observer's visibility thresholds (as listed in IntersectionObserver.thresholds, the observer's callback is executed with an IntersectionObserverEntry representing the intersection change which occurred. Note that this design allows multiple elements' intersection changes to be processed by a single call to the callback using an array of IntersectionObserverEntry objects.





An element whose visibility within the root is to be monitored. This element must be a descendant of the root element (or contained wtihin the current document, if the root is the document's viewport).

Return value





Specification Status Comment
Intersection Observer
The definition of 'IntersectionObserver.observe()' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 51.0 No support[1] 55 (55)[2] No support ? ?
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support 51.0 55.0 (55)[2] No support No support ? ? 51.0

[1] This feature is available since the Windows Insider Preview Build 14986.

[2] This feature has been implemented since Gecko 53.0 (Firefox 53.0 / Thunderbird 53.0 / SeaMonkey 2.50) behind the preference dom.IntersectionObserver.enabled, which was false by default. Enabled by default beginning in Firefox 55. See bug 1243846.

See also

Document Tags and Contributors

 Contributors to this page: tazsingh, Sheppy
 Last updated by: tazsingh,