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.
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
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
elementwhose 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).
The definition of 'IntersectionObserver.observe()' in that specification.
|Editor's Draft||Initial definition.|
|Feature||Chrome||Edge||Firefox (Gecko)||Internet Explorer||Opera||Safari (WebKit)|
|Basic support||51.0||No support||55 (55)||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)||No support||No support||?||?||51.0|
 This feature is available since the Windows Insider Preview Build 14986.
 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.