Bliss.js : Want to use Vanilla JS but find native APIs a bit unwieldy? Bliss is for you
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 ...
DOMAssistant : The modular lightweight JavaScript library, with CSS selectors, event handling, AJAX and complete Unicode support
Prototype : Easy Ajax and DOM manipulation for dynamic web applications
Zepto.js : Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zept...
Library to detect when DOM elements become visible and disappear on scroll.