Load image into canvas

gistfile1.txt

<canvas id="canvas"></canvas>
<script type="text/javascript">
    var can = document.getElementById('canvas');
    var ctx = can.getContext('2d');

    var img = new Image();
    img.onload = function(){
        can.width = img.width;
        can.height = img.height;
        ctx.drawImage(img, 0, 0, img.width, img.height);
    }
    img.src = 'test.jpg';

</script>