html5 动画精灵

<!DOCTYPE HTML>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <div style="position:absolute;top:50px;left:50px;"></div>
    <canvas id="canvas" width="80" height="98"></canvas>
    <script type="text/javascript">
    window.addEventListener("load", eventWindowLoaded,false);
    function eventWindowLoaded(){
        canvasApp();
    }
    function canvasApp(){
        var theCanvas=document.getElementById("canvas");
        var context=theCanvas.getContext('2d'); 

        counter=0;
        var tileSheet = new Image();
        tileSheet.addEventListener('load', eventShipLoaded , false);
        tileSheet.src = "1.png";
        function eventShipLoaded() {
            startUp();
        }
        function drawScreen() {
            context.fillStyle = "white";
            context.fillRect(0,0,500,500);
            context.drawImage(tileSheet,80*counter,288,80,96,0,0,80,96);
            counter++;
            if (counter>1) {
                counter=0;
            }
        }
        function startUp(){
            setInterval(drawScreen, 200);
        }
    }
    </script>
</body>
</html>
html5 动画精灵