Prototype : Easy Ajax and DOM manipulation for dynamic web applications
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 ...
Autotrack : Automatic and enhanced Google Analytics tracking for common user interactions on the web.
loglevel : Minimal lightweight logging for JavaScript, adding reliable log level methods to wrap any available console.log methods
Modest Maps is a small, extensible, and free library for designers and developers who want to use interactive maps in their own projects.