Vex : Vex is a modern dialog library which is highly configurable, easily stylable, and gets out of the way. You'll love vex because it's tiny (6kb minified...
enquire.js : A lightweight, pure JavaScript library for responding to CSS media queries.
Prototype : Easy Ajax and DOM manipulation for dynamic web applications
Scrollama : Scrollama is a modern & lightweight JavaScript library for scrollytelling using IntersectionObserver in favor of scroll events. The goal of this libra...
Headroom.js is a lightweight, high-performance JS widget (with no dependencies!) that allows you to react to the user's scroll.