jQuery.isInView is a jQuery plugin that tells you if elements are in view inside a scrollable container, or inside a container hiding its overflow – and does it blazingly fast, made for hot code paths.
Scrollspy is a jQuery plugin for detecting enter/exit of elements in the viewport when the user scrolls.
isInViewport.js is an ultra-light jQuery plugin that tells you if the element is in the viewport, but with a twist. It lets you select a visible element(s) using the
:in-viewport selector or by calling the
.isInViewport() method on the element(s).