Edit in JSFiddle

  <script src="http://files.cnblogs.com/iamzhanglei/JscexMin.js" type="text/javascript"></script>
  <canvas id="myCanvas" width="600" height="500" style="border:15px solid gray;
-moz-border-radius-bottomleft:40px;
-moz-border-radius-bottomright:40px;
-webkit-border-bottom-left-radius:40px;
-webkit-border-bottom-right-radius:40px;
-webkit-border-top-left-radius:40px;
-webkit-border-top-right-radius:40px;">
Your browser does not support the canvas element.
</canvas>
    <script type="text/javascript">
        var c = document.getElementById("myCanvas");
        var cxt = c.getContext("2d");
        cxt.lineWidth = 16;

        var startX = 250;
        var startY = 250;
        var drawHeart = eval(Jscex.compile("async", function () {
            var a = 112;
            for (var i = -400; i < 360; i++) {
                cxt.strokeStyle ="#FF0000";
                x = a * (1 - Math.sin(i * Math.PI / 360)) * Math.cos(i * Math.PI / 360);
                y = a * (1 - Math.sin(i * Math.PI / 360)) * Math.sin(i * Math.PI / 360);
                cxt.lineTo(startX + x, startY - y);
                cxt.stroke();
                $await(Jscex.Async.sleep(10))
            }   
        }))
        
    </script>
    <style type="text/css">
input.css3btn{
  background: -moz-linear-gradient(270deg, #d2ebf8, #0c8ab5);
  background: -webkit-linear-gradient(top, #d2ebf8, #0c8ab5);
  background: -o-linear-gradient(top, #d2ebf8, #0c8ab5);
  filter:progid:DXImageTransform.Microsoft.Gradient(GradientType=0, StartColorStr='#000099CC', EndColorStr='#FF0087B4');
  border-top: 1px solid #38538c;
  border-right: 1px solid #1f2d4d;
  border-bottom: 1px solid #151e33;
  border-left: 1px solid #1f2d4d;
  border-radius: 4px;
  box-shadow: inset 0 1px 10px 1px #5c8bee, 0px 1px 0 #1d2c4d, 0 2px 0px #1f3053, 0 4px 4px 1px #111111;
  color:#f0f0f0;
  font: bold 20px "helvetica neue", helvetica, arial, sans-serif;
  padding: 10px 0 10px 0;
  text-align: center;
  text-shadow: 0px -1px 1px #1e2d4d;
  width: 150px;
   background-clip: padding-box; }
  input.css3btn:hover {
    box-shadow: inset 0 0px 20px 1px #87adff, 0px 1px 0 #1d2c4d, 0 3px 0px #1f3053, 0 4px 4px 1px #111111;
    cursor: pointer; }
  input.css3btn:active {
    box-shadow: inset 0 1px 10px 1px #5c8bee, 0 1px 0 #1d2c4d, 0 2px 0 #1f3053, 0 4px 3px 0 #111111;
    margin-top: 1px; }
    </style>
    
    
    <input class="css3btn" value="运行" onclick="drawHeart().start();" type="button" />