Earlier quoted context omitted.
Great demo, well written code. Though reading through it also highlights that JS is not a great language for linear algebra. But I don't think anyone is really suggesting otherwise.
"JS is not a great language for linear algebra." what does that even mean? It's a general purpose language. It all boils down to how you want to use it, like any other general purpose language. A lot of times in cases like this, people choose not to make it look pretty and easy to read to gain performance. This simulation is very CPU intensive, trying to have pretty code and speed is going to be tough.
Not only tough but ultimately impossible; like C it is nice that people can stretch JS to maximize performance - a developer can always maintain separate file with "nicely" formulated calculations but at the end of the day what matters is the end user's experience of speed in the final app.