Squeme - Navier-Stokes Impressionism

code ? what is code ?
https://www.youtube.com/shorts/z_ukIw9wcL8

<html>
<body>
<script>        // the dropper math figure    function dropper(u,v) {
var svg = document.createElementNS("http://www.w3.org/2000/svg", "svg");
var height = document.body.clientHeight;
var width = document.body.clientWidth;
svg.setAttribute("width", width);
svg.setAttribute("height", height);
var radius = 0.8 * Math.min(height,width) / 2;
var nblines = Math.floor(Math.min(height,width))/2;
for (var i = -nblines ; i < nblines; i++) {
var line = document.createElementNS("http://www.w3.org/2000/svg","line");
line.setAttribute("id","line2");
line.setAttribute("x1",Math.cos(u * i) * radius + width/2);
line.setAttribute("y1",Math.sin(u * i) * radius + height/2);
line.setAttribute("x2",Math.cos(v * i) * radius + width/2);
line.setAttribute("y2",Math.sin(v * i) * radius + height/2);
line.setAttribute("stroke", "black");
line.setAttribute("stroke-opacity", (nblines - Math.abs(i)) / nblines);
svg.appendChild(line);
}
return svg;
}

   // time for animation
const timer = ms => new Promise(res => setTimeout(res, ms))   // choose two starting points for the dropper
var u = 3.141596 * (100 - Math.floor(Math.random()*200) / (Math.floor(Math.random()*100)+1));
var v = 3.141596 * (100 - Math.floor(Math.random()*200) / (Math.floor(Math.random()*100)+1));
// and choose two linear speeds for these points
var uv = 2e-5 - Math.random() * 4e-5;
var vv = 2e-5 - Math.random() * 4e-5;

   async function run() {
while(true) {
var svg = dropper(u,v);
document.body.appendChild(svg);
await timer(40);
document.body.removeChild(svg);
// then starting points must evolve slowly but constently
u += uv;
v += vv;
}
}

run();

</script>
</body>
</html>

output_13_negate.mp4

output_original_negate.mp4