var canvas = document.getElementById("demo")
   var ctx = canvas.getContext('2d');
   ctx.font = "32pt Arial";
   ctx.beginPath();
   ctx.lineWidth = "1";
   ctx.strokeStyle = "blue";
   ctx.moveTo(100, 100);
   ctx.lineTo(100, 400);
   ctx.lineTo(400, 400);
   ctx.lineTo(400, 100);
   ctx.closePath();
   ctx.stroke();
   ctx.strokeText("hello world hello world hello world hello world hello world", 120, 200);
   ctx.strokeStyle = "red";
   ctx.stroke();