Barnsley Fern in JavaScript (and Canvas)

fern.js

// paste this in a codepen, JSBin, etc
// https://rosettacode.org/wiki/Barnsley_fern#JavaScript

var d = document;
var cv = d.createElement("canvas");
d.body.appendChild(cv);
var c = cv.getContext("2d");
var cw = 300;
var ch = 300;
cv.width = cw;
cv.height = ch;
var x = 0,
  y = 0,
  xw = 0,
  yw = 0,
  r;
function rand(m) {
  return Math.floor(Math.random() * m);
}
c.fillStyle = "#fff";
c.fillRect(0, 0, cw, ch);
for (var i = 0; i < 10000; i++) {
  r = rand(100);
  if (r <= 1) {
    xw = 0;
    yw = 0.16 * y;
  } else if (r <= 8) {
    xw = 0.2 * x - 0.26 * y;
    yw = 0.23 * x + 0.22 * y + 1.6;
  } else if (r <= 15) {
    xw = -0.15 * x + 0.28 * y;
    yw = 0.26 * x + 0.24 * y + 0.44;
  } else {
    xw = 0.85 * x + 0.04 * y;
    yw = -0.04 * x + 0.85 * y + 1.6;
  }
  x = xw;
  y = yw;
  c.fillStyle = "#0a0";
  c.fillRect(x * cw * 0.05 + cw / 2, -y * ch * 0.06 + ch * 0.9, 1, 1);
}