Javascript Spiral

Drawing a spiral with the canvas and javascript

HTML

<!DOCTYPE html>
<html>
    <head>
        <title>archimedes spiral</title>
        <style type="text/css">
            canvas {border: 1px solid #000000;}
            </style>
    </head>
 
    <body>
        <canvas width="400" height="400" id="pageCanvas">
            You do not have a canvas enabled browser
        </canvas>
        
    </body>
</html>

JavaScript

var context = document.getElementById('pageCanvas').getContext('2d');
var n = 1;
lastX = 0;
lastY = 0;

<!-- clear the drawing surface -->
context.clearRect(0,0,400,400);

context.save();
context.lineWidth = 1;
context.translate(200,200);
context.moveTo(0,0);
var radius=200;
var samples=256;
var a = 0;
var b = 3;
for(i = 0; i <= (radius/b) + radius%b; i+=((radius/b)/samples)) {
    r = a + (b*i);
    x = r * Math.cos(i);
    y = r * Math.sin(i);
    context.lineTo(x,y);
}
context.stroke();
context.restore();