HTML

<!DOCTYPE html>
<html> 
  <head><title>Bubble Popper Game</title></head>
  <body>
  <script src="bubble.js"></script>
  </body>
</html>

JAVASCRIPT

const canvas = document.createElement('canvas');
canvas.setAttribute('height','480');
canvas.setAttribute('width','640');
canvas.style.backgroundColor = 'black';
document.body.prepend(canvas);
const ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.fillStyle = 'red';
ctx.strokeStyle = 'blue';
ctx.arc(canvas.width/2,canvas.height/2,50,0,Math.PI*2);
ctx.fill();
ctx.stroke();