<div>

        <p>绘制圆形</p>

        <canvas id="myCanvas" width="400" height="400"></canvas>

        <script language="javascript">

            var canvas = document.getElementById('myCanvas');

            var ctx = canvas.getContext('2d');

            ctx.beginPath();

            ctx.arc(100,100,100,0,Math.PI*2,true);

            ctx.fillStyle = '#FF6600';

            ctx.fill();

        </script>

    </div>