#### Experimental

**This is an experimental technology**

Check 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 Observer The definition of 'IntersectionObserverEntry.intersectionratio' in that specification. |
Working Draft | Initial definition |

## Browser compatibility

BCD tables only load in the browser

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.