intersection_observer library Null safety

Intersection Observer


The IntersectionObserver interface of 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 element or viewport is referred to as the root. [...]
The IntersectionObserverEntry interface of the Intersection Observer API describes the intersection between the target element and its root container at a specific moment of transition. Instances of are delivered to an IntersectionObserver callback in its entries parameter; otherwise, these objects can only be obtained by calling IntersectionObserver.takeRecords().