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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() constructor creates a new IntersectionObserver object.


var observer = new IntersectionObserver(callback, options);


A reference to a function that takes the following parameters:
Options are as follows:
  • root: A specific ancestor of the target being observed. The default is the viewport.
  • rootMargin: An offset to apply to the root's bounding_box when calculating intersections, effectively shrinking or growing the root for calculation purposes. The default is "0px 0px 0px 0px".
  • threshold: An array of values where callback will be called. A threshold is a ratio of intersection area to bounding box area of an observed target.  Thresholds can be any value between 0.0 and 1.0, inclusive.


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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 51.0 ? ? ? ?
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support 51.0 ? ? ? ? ? 51.0

Document Tags and Contributors

 Contributors to this page: jpmedley
 Last updated by: jpmedley,