Three.js is a cross-browser JavaScript library and application programming interface (API) used to create and display animated 3D computer graphics in a web browser using WebGL. The source code is hosted in a repository on GitHub (not this one obviously). Three.js allows the creation of graphical processing unit (GPU)-accelerated 3D animations using the JavaScript language as part of a website without relying on proprietary browser plugins.
If you have the will to study it ,it's actually really interesting. You can make super-advanced graphical objects and animations that use tons of math and plenty of creativity.
Wooden bench.Luminous balls. Flying sword. Balls going around pillars. Bulgarian flag on some weird kind of a pyramid rock. Balls around Torus. Balls on a trip around Borisova gradina . Did I also mentioned balls? And stuff that I am not sure I can explain properly so why don't you check it yourself ?