JS1k: The JavaScript code golfing competition

var c = document.getElementById('c'),
	$ = c.getContext('2d'),
	_ = [],
	s = 300,
	m = Math,
	l = 40,
	n = 20;
m.r = m.random;
c.width = s;
c.height = s;
$.fillStyle = '#000';
$.lineWidth = 13;

function x() {
	return m.floor(m.r()*255.9);
}

function Tile() {
	var a = m.r()*2;
	return {
		t: +new Date(),
		c: 'rgba('+x()+','+x()+','+x()+',',
		w: 0.1,
		l: (1+m.r())/3,
		s: a,
		z: a,
		r: m.r()
	};
}

for (var i=0; i<l; i++) _[i] = new Tile();

setInterval(function() {
	var t = +new Date(),
		h = s/2,
		r = m.sqrt(s*h),
		p = 1/n;

	$.fillRect(0,0,s,s);
	
	for (var i=0; i<l; i++) {
		var a = _[i],
			d = (a.s + 0.0015*(t-a.t)) % 2;
		a.z = d - 1;
	}
	
	for (var o=p; o<=1; o+=p) {
		for (var i=0; i<l; i++) {
			if ((o>_[i].z) && (_[i].z+_[i].l>o)) {
				var a = _[i],
					e = 2*m.PI*a.r;
				$.strokeStyle = a.c+o+')';
				$.beginPath();
				$.arc(h,h,r*o,e,e-2*m.PI*a.w,true);
				$.stroke();
			}
		}
	}
}, 1000/35);

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

var c = document.getElementById('c'),
	$ = c.getContext('2d'),
	_ = [], // tiles
	s = 300, // size 300x300
	m = Math,
	l = 40, // # of tiles
	n = 20; // # of circles
m.r = m.random;
c.width = s;
c.height = s;
$.fillStyle = '#000';
$.lineWidth = 13;

// random 0..255
function x() {
	return m.floor(m.r()*255.9);
}

// tile class
function Tile() {
	var a = m.r()*2;
	return {
		t: +new Date(), // creatin time
		c: 'rgba('+x()+','+x()+','+x()+',', // color w/o alpha channel
		w: 0.1, // width
		l: (1+m.r())/3, // length
		s: a, // start position (depth)
		z: a, // current position (depth)
		r: m.r() // position (radial)
	};
}

// generating tiles
for (var i=0; i<l; i++) _[i] = new Tile();

// main
setInterval(function() {
	var t = +new Date(), // current time
		h = s/2, // half of size
		r = m.sqrt(s*h), // max radius
		p = 1/n; // step = 1 / # circles

	$.fillRect(0,0,s,s); // background
	
	for (var i=0; i<l; i++) {
		var a = _[i],
			d = (a.s + 0.0015*(t-a.t)) % 2; // 0.0015 - speed
		a.z = d - 1; // new position, start from -1
	}
	
	for (var o=p; o<=1; o+=p) { // depth and opacity
		for (var i=0; i<l; i++) {
			if ((o>_[i].z) && (_[i].z+_[i].l>o)) {
				var a = _[i],
					e = 2*m.PI*a.r;
				$.strokeStyle = a.c+o+')'; // + opacity
				$.beginPath();
				$.arc(h,h,r*o,e,e-2*m.PI*a.w,true); // draw it!
				$.stroke();
			}
		}
	}
}, 1000/35); // 35 fps max