Simple Software Renderer

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Simple Software Renderer</title>
  </head>
  <body>
    <canvas width="1280" height="720"></canvas>
    <script type="text/javascript">
window.onload = function () {
  var ctx = document.getElementsByTagName('canvas')[0].getContext('2d');
  var idx = 0;
  var w = ctx.canvas.width;
  var h = ctx.canvas.height;
  function idxFilename(idx) {
    return '' + '00000000'.slice(('' + idx)['length']) + idx + '.png';
  }
  function handleBlob(blob) {
    var req = new XMLHttpRequest();
    req.open('POST', idxFilename(++idx), true);
    req.onload = handleRequest;
    req.send(blob);
  }
  function handleRequest() {if (draw()) ctx.canvas.toBlob(handleBlob)}
  function draw() {
    //
  }
  handleRequest();
}
    </script>
  </body>
</html>