DOMAssistant : The modular lightweight JavaScript library, with CSS selectors, event handling, AJAX and complete Unicode support
Bliss.js : Want to use Vanilla JS but find native APIs a bit unwieldy? Bliss is for you
Prototype : Easy Ajax and DOM manipulation for dynamic web applications
Styletron : Styletron is a universal CSS-in-JS engine built from the ground up for high-performance.
css3-mediaqueries-js : make CSS3 Media Queries work in all browsers (JavaScript library)
Anime.js is a fast, multipurpose and lightweight JavaScript animation library with a simple, yet powerful API.
It works with CSS properties, SVG, DOM attributes and JavaScript Objects.