createCanvas(400, 400);

  noStroke();

  var b = createButton("Generate pattern");

  b.mousePressed(pattern);

  pattern();

}

​

function pattern() {

  background(220);

  var cols = 24;

  var rows = 12;

  var w = width / cols;

  var h = height / rows;

  for (let x = 0; x <= width; x += w) {

    for (let y = 0; y <= height; y += h) {

      var pinkShade = color(random(255), random(150, 200), random(200, 255));

      fill(pinkShade);

      var xo = random(-w / 4, w / 4);

      var yo = random(-h / 2, h / 2);

      var d = random(w, h);

      ellipse(x + w / 2 + xo, y + h / 2 + yo, d, d);

    }

  }

}