<canvas width="600" height="400"></canvas>
<script>
function desenhaQuadrado(x, y, cor) {
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
pincel.fillStyle = cor;
pincel.fillRect(x, y, 50, 50);
pincel.strokeStyle = 'black';
pincel.strokeRect(x, y, 50, 50);
}
var x = 0;
for ( var x = 0; x < 150; x = x + 50) {
desenhaQuadrado(x, 0, 'green');
}
desenhaQuadrado(150, 0, 'white');
</script>
