JS1k: The JavaScript code golfing competition

window.onload=function(){Q=Math.random;C=Math.cos;S=Math.sin;U=0;w=window;d=document.getElementById("c");c=d.getContext("2d");W=d.width=w.innerWidth;H=d.height=w.innerHeight;c.fillRect(0,0,W,H);c.globalCompositeOperation="lighter";c.lineWidth=0.2;var a=false,e=Q()*99,f=Q()*99,g=Q()*99,b=0;d.onmousemove=function(l){if(window.T){n=5;while(n--){go(1)}clearTimeout(T)}X=l.pageX;Y=l.pageY;var k,j,h=X,m=Y;e=(l.pageX/W*1000>>0)/1000;f=(l.pageY/H*1000>>0)/1000;U=l.pageX/H*360>>0;g=25;T=setInterval(go=function(o){c.save();c.globalCompositeOperation="source-over";if(!o){c.fillStyle="rgba(0,0,0,0.015)";c.fillRect(0,0,W,H)}c.restore();i=25;while(i--){if(g>400||a){if(!a){e+=0.05;a=true}if(g<0.1){e+=0.05;a=false}g-=0.1}if(!a){g+=0.1}q=(e/f-1)*b;x=(e-f)*C(b)+g*C(q)+(h+(X-h)*(i/30))+(f-e);y=(e-f)*S(b)-g*S(q)+(m+(Y-m)*(i/30));if(k){c.moveTo(k,j);c.lineTo(x,y)}c.strokeStyle="hsl("+(U%360)+",100%,50%)";c.stroke();c.beginPath();b+=360*Math.PI/180*2;k=x;j=y}U-=0.5;h=X;m=Y},20);go()};d.onmousemove({pageX:410,pageY:207.5})};

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window.onload = function () {
	Q = Math.random; // cache Math objects
	C = Math.cos;
	S = Math.sin;
	U = 0;
	w = window;
	d = document.getElementById("c");
	c = d.getContext("2d");
	W = d.width = w.innerWidth;
	H = d.height = w.innerHeight;
	c.fillRect(0, 0, W, H); // resize <canvas> and draw black rect (default)
	c.globalCompositeOperation = "lighter"; // switch to additive color application
	c.lineWidth = 0.2;
	var bool = false, 
		R = Q() * 99, // rolling circle radius
		r = Q() * 99, // fixed circle radius
		D = Q() * 99, // distance
		t = 0; // theta
	d.onmousemove = function (e) {
		if(window.T) {
			n = 5; while(n--) go(1);
			clearTimeout(T);
		}
		X = e.pageX; // grab mouse pixel coords
		Y = e.pageY;
		var a, // previous coord.x
			b, // previous coord.y 
			A = X, // original coord.x
			B = Y; // original coord.y
		R=(e.pageX/W * 1000>>0)/1000;
		r=(e.pageY/H * 1000>>0)/1000;
		U=e.pageX/H * 360 >>0;
		D=25;
		T = setInterval(go = function (boo) { // start looping spectrum
			c.save();
			c.globalCompositeOperation = "source-over"; // switch to additive color application
			if(!boo) {
				c.fillStyle = "rgba(0,0,0,0.015)";
				c.fillRect(0, 0, W, H); // resize <canvas> and draw black rect (default)
			}
			c.restore();
			i = 25; while(i --) {
				if(D > 400 || bool) { // decrease diameter
					if(!bool) { // has hit maximum
						R += 0.05;
						bool = true;
					}
					if(D < 0.1) { // has hit minimum
						R += 0.05;
						bool = false;
					}
					D -= 0.1; 
				}
				if(!bool) { // increase diameter
					D += 0.1;
				}
				q = (R / r - 1) * t; // create hypotrochoid from current mouse position, and setup variables (see: http://en.wikipedia.org/wiki/Hypotrochoid)
				x = (R - r) * C(t) + D * C(q) + (A + (X - A) * (i / 30)) + (r - R); // center on xy coords
				y = (R - r) * S(t) - D * S(q) + (B + (Y - B) * (i / 30));
				if (a) { // draw once two points are set
					c.moveTo(a, b);
					c.lineTo(x, y)
				}
				c.strokeStyle = "hsl(" + (U % 360) + ",100%,50%)"; // draw rainbow hypotrochoid
				c.stroke();
				c.beginPath();
				t += 360 * Math.PI / 180 * 2; // increment theta
				a = x; // set previous coord.x
				b = y; // set previous coord.y
			}
			U -= 0.5; // increment hue
			A = X; // set original coord.x
			B = Y; // set original coord.y
		}, 20);
		go();
	}
	d.onmousemove({pageX:410, pageY:207.5})
}