<canvas width="600px" height="400px" ></canvas>
<script>
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
pincel.fillStyle = 'lightgray';
pincel.fillRect(0, 0, 600, 400);
function desenhaCirculo(x, y, raio, cor) {
pincel.fillStyle = cor;
pincel.beginPath();
pincel.arc(x, y, raio, 0, 2*3.14);
pincel.fill();
}
desenhaCirculo(300,200,2*3.14,'red')
desenhaCirculo(288,200,2*3.14,'orange')
desenhaCirculo(312,200,2*3.14,'black')
desenhaCirculo(300,188,2*3.14,'yellow')
desenhaCirculo(300,212,2*3.14,'blue')
</script>
