Untitled

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Canvas</title>
</head>
<body>
<canvas id="myCanvas" width="600" height="600" >


</canvas>

  <script>
    window.addEventListener('load', draw);
    function draw() {
      var canvas = document.getElementById('myCanvas');
      var ctx = canvas.getContext('2d');
      ctx.fillStyle = "blue";
      ctx.fillRect(100, 100, 30, 30)
      ctx.fillRect(150, 150, 30, 30)
    }
  </script>


</body>
</html>