Lozad.js - Highly performant lazy loader in pure JS
JavaScript.com - A free resource for learning and developing in JavaScript
particles.js - A lightweight JavaScript library for creating particles.
A.I. Experiments by Google - Explore machine learning by playing w/ pics, music, and more
Dragula - A drag and drop library for developers
BundlePhobia - Find the performance impact of adding a npm package to your bundle.