console 命令行工具 X clear

console

function draw() {
  var ctx = document.getElementById('canvas').getContext('2d');

  ctx.save();
  ctx.scale(3, 3);
  ctx.fillRect(1, 10, 10, 10);
  ctx.restore();

  ctx.scale(-1, 1);
  ctx.font = '48px serif';
  ctx.fillText('MDN', -150, 60);
}

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