chroma.js is a small-ish zero-dependency JavaScript library (13.5kB) for all kinds of color conversions and color scales.

Replace Font Awesome with modern line icons.

Tiny (2 KB) turboboosted JavaScript library for creating user interfaces. - redom/redom

You've been looking for a more sophisticated templating engine for JavaScript. Here it is.

• Rich Powerful language with block inheritance, autoescaping, macros, asynchronous control, and more. Heavily inspired by jinja2
• Fast & Lean High-performant. Small 8K gzipped runtime with precompiled templates in the browser
• Extensible Crazy extensible with custom filters and extensions
• Everywhere Available in node and all modern web browsers, with thorough precompilation options

Milligram provides a minimal setup of styles for a fast and clean starting point. Just it! Only 2kb gzipped! It's not about a UI framework. Specially designed for better performance and higher productivity with fewer properties to reset resulting in cleaner code. Hope you enjoy!

PrimeReact is a collection of rich UI components for React. PrimeReact is a sibling of the popular PrimeNG (Angular) and PrimeFaces (JSF) components suites.

Anime.js is a lightweight JavaScript animation library with a simple, yet powerful API.
It works with CSS properties, SVG, DOM attributes and JavaScript Objects.

react-motion - A spring that solves your animation problems.

The Transition component lets you describe a transition from one component state to another over time with a simple declarative API. Most commonly it's used to animate the mounting and unmounting of a component, but can also be used to describe in-place transition states as well.

React implements a browser-independent DOM system for performance and cross-browser compatibility. We took the opportunity to clean up a few rough edges in browser DOM implementations.

 Block Element Modifier is a methodology that helps you to create reusable components and code sharing in front-end development

Easy

To use BEM, you only need to employ BEM’s naming convention.

Modular

Independent blocks and CSS selectors make your code reusable and modular.

Flexible

Using BEM, methodologies and tools can be recomposed and configured the way you like.