A Svelte component that monitors an element enters or leaves the viewport/parent element. Performant and efficient thanks to using Intersection Observer under the hood. Can be used in multiple projects including lazy loading images, infinite scrolling, playing/pausing the video when in the viewport, tracking user behaviour firing link pre-fetching and animations and many many more.

It's a generic abstraction for the logic and styling of elements that pop out from the flow of the document and float next to a reference element, overlaid on top of the UI.

Is there something like instance variables? Yes! The useRef() Hook isn’t just for DOM refs. The “ref” object is a generic container whose current property is mutable and can hold any value, similar to an instance property on a class.