Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/37863
This creates 2 examples for IntersectionObserver in RNTester:
* The first example is just a copy of the example provided by MDN in the documentation page for `IntersectionObserver` (https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API). This example is useful to show how React Native behaves the same way with the same code.
* The second example is a "stress test" for the API: a screen with 500 simultaneous node being observed at the same time with different observers. As we compute the intersections after scroll (after "mounting" the state update with the updated scroll position) in the main thread, this highlights a possible impact on scroll performance.
IntersectionObserver isn't yet enabled by default, so no need to add a changelog entry about this. We'll add one when the API becomes generally available.
Changelog: [Internal]
Reviewed By: rshest
Differential Revision: D45736845
fbshipit-source-id: 40b6bce39f90e04653504b1033a4edfaa65e93ca
Moti Zilberman
Rubén Norte