Web/API/IntersectionObserverEntry/intersectionRatio

This is an experimental technologyCheck the Browser compatibility table carefully before using this in production.

The IntersectionObserverEntry interface's read-only intersectionRatio property tells you how much of the target element is currently visible within the root's intersection ratio, as a value between 0.0 and 1.0.

Syntax

var intersectionRatio = IntersectionObserverEntry.intersectionRatio;

Value

A number between 0.0 and 1.0 which indicates how much of the target element is actually visible within the root's intersection rectangle. More precisely, this value is the ratio of the area of the intersection rectangle (intersectionRect) to the area of the target's bounds rectangle (boundingClientRect).

If the area of the target's bounds rectangle is zero, the returned value is 1 if isIntersecting is true or 0 if not.

Example

In this simple example, an intersection callback sets each target element's opacity to the intersection ratio of that element with the root.

function intersectionCallback(entries) {
  entries.forEach(function(entry) {
    entry.target.style.opacity = entry.intersectionRatio;
  });
}

To see a more concrete example, take a look at Handling intersection changes in Timing element visibility with the Intersection Observer API.

Specifications

Specification	Status	Comment
Intersection ObserverThe definition of 'IntersectionObserverEntry.intersectionratio' 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
`intersectionRatio` 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 ?	WebView Android Full support 51	Chrome Android Full support 51	Firefox Android ?	Opera Android ?	Safari iOS ?	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.

IntersectionObserverEntry.intersectionRatio by Mozilla Contributors is licensed under CC-BY-SA 2.5.