Untitled

<!DOCTYPE html>

<html>
    <head>
        <link href="css/styless.css" type="text/css" rel="stylesheet">
        <script type="text/javascript">
            window.addEventListener("load", app);
            function app() {
                var canvas = document.getElementById("canvas1");
                var context = canvas.getContext("2d");
                context.fillStyle = "#FFFFFF";
                context.fillRect(0, 0, canvas.width, canvas.height);
                context.fillStyle = "#0080FF";
                context.beginPath();
                context.arc(400, 300, 100, 0, 2*Math.PI, true);
                context.stroke();
                context.fill();
            }
        </script>
    </head>
    <body>
        <canvas id="canvas1" width="800px" height="600px"></canvas>
    </body>
</html>