viewprt is a tiny, dependency‑free JavaScript library that watches elements’ visibility and a container’s scroll position relative to the viewport. It provides `ElementObserver` for enter/exit callbacks and `PositionObserver` for detecting when a viewport reaches its edges, making it useful for lazy‑loading, infinite scroll, or any custom scroll‑based UI logic. It’s aimed at front‑end developers who need a high‑performance, zero‑dependency solution for viewport intersection and positioning.