wiggler.js

var els = [],
g = {
	img: document.getElementsByTagName("img")[0],
	time:  0,
	amt:   20,
	amin:  5 /* amp */,
	amax:  10,
	ramin: 1 /* rot amp */,
	ramax: 50,
	pmin:  1 /* period */,
	pmax:  10,
	rpmin: 1 /* rot period */,
	rpmax: 50
};

function randf(min,max) { return Math.random()*(max-min)+min; }

function randSign() { return Math.round(Math.random()) ? -1 : 1; }

function sin(amp,period) { return amp*Math.sin((g.time/period)*2*Math.PI); }

function generateVariables() {
	for(var i = els.length; i < g.amt; i++) {
		els.push(
			{
				el: document.body.appendChild(g.img.cloneNode()),
				t:  randf(0, document.body.scrollHeight),
				l:  randf(0, window.innerWidth),
				ax: randf(g.amin,  g.amax),
				ay: randf(g.amin,  g.amax),
				ar: randf(g.ramin, g.ramax),
				px: randf(g.pmin,  g.pmax) * randSign(),
				py: randf(g.pmin,  g.pmax) * randSign(),
				pr: randf(g.rpmin, g.rpmax) * randSign()
			}
		);
		l = els[i];
		l.el.style.position = "absolute";
		l.el.style.zIndex   = 9e10 * randSign();
		l.el.style.top      = l.t + "px";
		l.el.style.left     = l.l + "px";
		l.el.style.width    =
		l.el.style.height   = randf(1, 40) + "%";
	}
}

function startLoop() {
	for(var i = 0; i < els.length; i++) {
		var l = els[i];
		l.el.style.top       = l.t + sin(l.ay, l.py) + "px";
		l.el.style.left      = l.l + sin(l.ax, l.px) + "px";
		l.el.style.transform = "rotate(" + sin(l.ar, l.pr) + "deg)";
	}
	g.time += 0.03;
	window.requestAnimationFrame(startLoop);
}

generateVariables();
startLoop();