Wave.js : Audio visualizer library for javascript. Create dynamic animations that react to an audio file or audio stream.
Frappe Charts : GitHub-inspired simple and modern charts for the web with zero dependencies.
JSDB.io : JSDB is a collection of the best javascript libraries
Push by Nickersoft : A compact, cross-browser solution for using the JavaScript Notifications API
darken : Easy control over your dark mode in a web environment
Rainbow is a code syntax highlighting library written in Javascript.
It was designed to be lightweight (1.4kb), easy to use, and extendable.
It is completely themable via CSS.