console 命令行工具 X clear

console

function draw() {
  var ctx = document.getElementById('canvas').getContext('2d');
  for (var i = 0; i < 3; i++) {
    for (var j = 0; j < 3; j++) {
      ctx.save();
      ctx.fillStyle = 'rgb(' + (77 * i) + ', ' + (255 - 77 * i) + ', 255)';
      ctx.translate(10 + j * 50, 10 + i * 50);
      ctx.fillRect(0, 0, 25, 25);
      ctx.restore();
    }
  }
}

<html>
 <body onload="draw();">
   <canvas id="canvas" width="300" height="300"></canvas>
 </body>
</html>