A small, fast, modern, and dependency-free library for lazy loading.
js
jQuery.fracs
“determines the fraction of an HTML element that is currently in the viewport, as well as the fraction it takes of the complete viewport and the fraction of the area that might possibly be visible. It also provides the coordinates of the visible rectangle in document, element and viewport space.”
Introduction to the Page Visibility API
This could save a lot of bandwidth and user CPU over time: “If a page is minimized or hidden behind another tab, it may not make sense to continue functionality such as polling the server for updates or performing an animation. The Page Visibility API aims to give developers information about whether or not the page is visible to the user.”
Microjs
“Microjs.com helps you discover the most compact-but-powerful microframeworks, and makes it easy for you to pick one that’ll work for you. “