Leaflet : A Modern, Lightweight Open-Source JavaScript Library for Interactive Maps
SoundManager 2 : Using HTML5 and Flash, SoundManager 2 provides reliable cross-platform audio under a single JavaScript API.
Prototype : Easy Ajax and DOM manipulation for dynamic web applications
Band.js : An interface for the Web Audio API that supports rhythms, multiple instruments, repeating sections, and complex time signatures.
React : A JavaScript library for building user interfaces
Scrollama is a modern & lightweight JavaScript library for scrollytelling using IntersectionObserver in favor of scroll events. The goal of this library is to provide a simple interface for creating scroll-driven interactives
Autoprefixer : PostCSS plugin to parse CSS and add vendor prefixes to CSS rules using values from Can I Use.
Woah.css : CSS Animation Library for eccentric web developers.
Animate.css : Animate.css is a bunch of cool, fun, and cross-browser animations for you to use in your projects.
Anime.js : Anime.js is a fast, multipurpose and lightweight JavaScript animation library with a simple, yet powerful API.
It works with CSS properties, SVG, DOM ...
Selectivizr : CSS3 pseudo-class and attribute selectors for IE 6-8
Animate On Scroll Library.
Small library to animate elements on your page as you scroll.