Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/47908
Changelog: [General][Added] - Add support for `rn_rootThreshold` in Intersection Observer
`rn_rootThreshold` is a custom IntersectionObserver option and not part of the IntersectionObserver spec. We are adding it because it covers a specific use-case for measuring viewability that is robust for `target`s that are larger than the viewport or specified `root`.
The threshold ratio is of the intersection area (of `root` and `target`) to the total area of the `root`.
{F1960832959}
Source - EX314979
`rn_rootThreshold` is an optional threshold and can be combined with the `thresholds` option. An intersection will fire if any specified thresholds is met.
Note: If you use specify a `rn_rootThreshold`, the default `threshold` is no longer applied
The main use case of `rn_rootThreshold` is being able to specify a level of viewability independent of `target` size. For example, a `target` that is larger than the `root` (commonly the viewport) will not trigger the IntersectionObserver for a `threshold` of `1`. Setting `rn_rootThreshold` of `1`, will trigger once the item takes full size of the `root`.';
Reviewed By: yungsters
Differential Revision: D66031119
fbshipit-source-id: 7bdc871dc5b4e6c0edc7d6e17a0a0cfd51c4fe81
Luna Wei