<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<style>
div {
margin: 3px;
width: 40px;
height: 40px;
position: absolute;
left:0;
top: 0;
background: green;
}
</style>
<script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
<div></div>
<script>
var div = $( "div" );
function runIt() {
div.animate({ left: 30 }, 500 )
.animate({ top: 30 }, 500 )
.animate({ left: "-=30" }, 500 )
.animate({ top: "-=30" }, 500, function() {
runIt()
});
}
runIt();
</script>
</body>
</html>