var GRAVITY = 0.08;
var SPEED = 1; //1 is fastest
var dx = [];
var dy = [];
var maxX = window.innerWidth;
var maxY = window.innerHeight;
var all = [];// = document.getElementsByTagName("*:visible");
var positions = [];
var widths = [];
var heights = [];
function drop() {
$("*").each(function(index) {
all.push(this);
positions.push($(this).offset());
widths.push($(this).width());
heights.push($(this).height());
});
for(var i=0; i < all.length; i++) {
all[i].style.position = "fixed";
all[i].style.top = positions[i].top+"px";
all[i].style.left = positions[i].left+"px";
dx[i] = Math.random() * 4 - 2;
dy[i] = Math.random() * 1;
}
setInterval(mainLoop, SPEED);
}
function mainLoop() {
for(var i=0; i < all.length; i++) {
dy[i] += GRAVITY/2;
positions[i].top += dy[i];
positions[i].left += dx[i];
dy[i] += GRAVITY/2;
if(positions[i].left < 0) dx[i] *= -1;
if((positions[i].left + all[i].offsetWidth) > maxX) dx[i] *= -1;
if(positions[i].top > (maxY - all[i].offsetHeight)) dy[i] = -Math.abs(dy[i]);
all[i].style.left = positions[i].left+"px";
all[i].style.top = positions[i].top+"px";
}
}
drop();<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<html>
<body>
<div style="border-style: solid; border-width: 5px; border-color:red;">Test</div>
</body>
</html>