This is also a beautiful animation made on HTML5 canvas.
In order to draw the curve, two parametric equations are derived from the polar equation in this animation. It is described below in detail.
Finding a good book to master HTML5 can be very challenging: there are so many around - most with eye-catching titles and very complex substance.
Therefore,
Vivax Solutions strongly recommends
Core HTML5 Canvas for those who really want to delve into HTML5.
Please click the image to access
Amazon:
<script>
var canvas = document.getElementById('Canvas_One');
var context = canvas.getContext('2d');
var i = 0; j = 0.1, t = 0;
var col = new Array('green', 'blue', 'red', 'cyan', 'magenta', 'yellow');
function timing() {
t = t + 1;
i = i + j;
var r = 150 * Math.cos(2 * i);
if (t > 5) { t = 0; }
//var r=Math.pow(10000*Math.cos(2*i),0.5);
var x = 200 + r * Math.sin(i); var y = 200 + r * Math.cos(i);
//context.font="40px Georgia";
//context.textAlign='center';
//context.fillText('.',x,y);
//context.fillStyle='purple';
context.beginPath();
context.moveTo(200, 110);
context.lineTo(x, y);
context.lineCap = 'round';
context.strokeStyle = 'rgba(0,0,255,0.5)';
context.stroke();
context.beginPath();
context.moveTo(200, 110);
context.arc(x, y, 5, 0, 2 * Math.PI);
context.fillStyle = col[t];
context.fill();
if (i > 6.4) { j = -0.1; context.clearRect(0, 0, 400, 400); }
if (i < -0.1) { j = 0.1; context.clearRect(0, 0, 400, 400); }
}
window.setInterval('timing()', 400);
</script>