Any idea what framework (if any) this is written in?
View the source of the articles and you will find thousands of lines of readable HTML, handwritten JavaScript using canvas and WebGL, and handwritten audio manipulation using window.AudioContext. Similar stories for the author's other incredible articles.
It's hand-crafted WebGL with no frameworks, which is insane. If you View Source on the page, you'll see that the JS is readable because he doesn't minify at all.