css.css

* {padding: 0; margin: 0; overflow: hidden; }
#canvas {background: black; }

html.html

<canvas id="canvas"></canvas>

js.js

// RequestAnimFrame: a browser API for getting smooth animations
window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       || 
		  window.webkitRequestAnimationFrame || 
		  window.mozRequestAnimationFrame    || 
		  window.oRequestAnimationFrame      || 
		  window.msRequestAnimationFrame     ||  
		  function( callback ){
			window.setTimeout(callback, 1000 / 60);
		  };
})();

// Initialize the canvas first with 2d context like 
// we always do.
var canvas = document.getElementById("canvas"),
		ctx = canvas.getContext("2d"),
	 
		// Now get the height and width of window so that
		// it works on every resolution. Yes! on mobiles too.
		W = window.innerWidth,
		H = window.innerHeight,
		
		counter = 0,
		particles = [];

// Set the canvas to occupy FULL space. We want our creation
// to rule, don't we?
canvas.width = W;
canvas.height = H;

function paintCanvas() {
	ctx.globalCompositeOperation = "source-over";
	ctx.fillStyle = "rgba(0,0,0,0.2)";
	ctx.fillRect(0, 0, W, H);
}

function Particle() {
	this.x = Math.random() * W;
	this.y = Math.random() * H;
	this.angle = Math.random() * 360;
	
	this.r = Math.floor(Math.random() * 255);
	this.g = Math.floor(Math.random() * 255);
	this.b = Math.floor(Math.random() * 255);
	
	this.color = "rgb("+ this.r +", "+ this.g +", "+ this.b +")";	
	
	this.draw = function() {
		ctx.beginPath();
		ctx.globalCompositeOperation = "lighter";
		ctx.fillStyle = this.color;
		ctx.arc(this.x, this.y, 1, 0, Math.PI*2, false);
		ctx.fill();
	}
}

for(var i = 0; i < 200; i++) { 
	particles.push(new Particle());	
}	
	
function draW() {
	paintCanvas();
	
	for(var i = 0; i < particles.length; i++) {
		var p = particles[i];
		
		p.draw();
		p.x += Math.sin(1.4);
		p.y += Math.cos(counter * Math.PI/p.angle);
		
		if(p.x > W)
			p.x = 0;
	}
	
	counter += 1;

}

console.log(particles);

function animloop() {
	draW();
	requestAnimFrame(animloop);
}

animloop();