What If Canvas Is Not Supported?
If you see the following message on your screen, Your browser does not support the HTML5 canvas element (which is the message between the <canvas> tags), you need to make sure that you're using one of the supported web browsers described earlier.
If you're using Firefox and you still see this message, you may want to check whether WebGL is enabled (it is by default). To do so, go to Firefox and type about:config in the address bar. Then, look for the webgl.disabled property. If it is set to true, change it to false. When you restart Firefox and load ch01_01_canvas.html, you should be able to see the dotted border of the canvas element.
In the remote case that you still do not see canvas, it could be because your browser has blacklisted your GPU. If this is the case, please use a system with the appropriate hardware.