animated bit patterns

<canvas id="c" width="768" height="768">
<script>
  const context = c.getContext('2d');

  function test(x,y,t) {
      return ((x * y)^t) % 17;
  }

  const scale = 2;

  function draw(t) {
      for (let x = 0; x < c.width / scale; x++) {
        for (let y = 0; y < c.height / scale; y++) {
          if (test(x,y,t)) {
            context.fillStyle = '#000';
           } else {
            context.fillStyle = '#fff';
      }

          context.fillRect(x*scale, y*scale, scale, scale);
        }
      }
  }

  let t = 0;

  window.setInterval(() => { t = (t+1) % 256; draw(t); }, 20);

</script>