JS Canvas Moving Down The Road Transparent Version SRC

<center><canvas id="canvas" width = "460" height = "360" </canvas>



        <script>
      c = document.getElementById("canvas");
var ctx = c.getContext("2d");

id = ctx.createImageData(460,360);

function draw() {
var w=c.width;
var h=c.height;
  window.requestAnimationFrame(draw);
    var r=11;
    for (var p = w * h+ (w + h); p >= 8; p -= 48) {
        r -= Math.random()*256;
    id.data[p++]=id.data[p++]=id.data[p+Math.floor(Math.random()*4)] = 1112 * Math.random()*Math.sqrt(4);
        id.data[p+4] = Math.random()*100;
    }
    ctx.putImageData(id, 1, 1);
}

draw();

    </script>
</body>
</html>