Intersection Observer

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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 interface of the the Intersection Observer API provides a way to asynchronously observe changes in the intersection of a target element with an ancestor element or with a top-level document's viewport. The ancestor or viewport is referred to as the root.

Constructor

IntersectionObserver.IntersectionObserver()
Creates a new IntersectionObserver object.

Properties

IntersectionObserver.root Read only
A specific ancestor of the element being observed. If no value was passed to the constructor, the top-level document's viewport is used.
IntersectionObserver.rootMargin Read only
An offset applied to the root's bounding_box when calculating intersections, effectively shrinking or growing the root for calculation purposes. This is not guaranteed to be identical to the value passed in the constructor. If no value was passed to the constructor, "0px 0px 0px 0px" is used. This property takes pixels ('px') or percentages ('%').
IntersectionObserver.thresholds Read only
A list of thresholds, sorted in increasing numeric order, where each threshold is a ratio of intersection area to bounding box area of an observed target. Notifications for a target are generated when any of the thresholds are crossed for that target. If no value was passed to the constructor, 0 is used.

Methods

IntersectionObserver.disconnect
Stops the IntersectionObserver object from observing any target.
IntersectionObserver.observe
Tells the IntersectionObserver a target element to observe.
IntersectionObserver.takeRecords
Returns an array of IntersectionObserverEntry objects for all observed targets and stops observing all of them.
IntersectionObserver.unobserve
Tells the IntersectionObserver to stop observing a particular target element.

Examples

var intersectionObserver = new IntersectionObserver(function(entries) {
  // If intersectionRatio is 0, the target is out of view
  // and we do not need to do anything.
  if (entries[0].intersectionRatio <= 0) return;

  loadItems(10);
  console.log('Loaded new items');
});
// start observing
intersectionObserver.observe(document.querySelector('.scrollerFooter'));

Specifications

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

Browser Compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support

51.0

52.0 (52.0) ? ? ?
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: yisibl, paul.irish, jpmedley
 Last updated by: yisibl,