Open source CSS custom properties to help accelerate adaptive and consistent design. Available from a CDN or NPM, as CSS or JavaScript.
You may also be interested in ...
Compressorjs
JavaScript image compressor. Uses the Browser's native canvas.toBlob API to do the compression work, which means it is lossy compression. General use this to precompress a client image file before upload it.
Chart.js
Simple yet flexible JavaScript charting for designers & developers. Charts.js is one of the most beautiful open source charts library.
Mithril, a JS SPA framework used by Vimeo, Nike and Lichess
Mithril.js is a modern client-side JavaScript framework for building Single Page Applications. It's small (8.8 KiB gzip), fast and provides routing and XHR utilities out of the box.