draw a circle on canvas

function drawCircle(canvas, x, y, radius, fillColor, lineColor) {
  c.beginPath();
  c.arc(x, y, radius, 0, Math.PI * 2, false);
  if (fillColor) {
    c.fillStyle = fillColor;
    c.fill();
  }
  if (lineColor) {
    c.strokeStyle = lineColor;
    c.stroke();
  }
}