<!DOCTYPE html>
<html>
<head>
<script>
function boom()
{
  var floater = document.createElement("span");
  floater.style.cssFloat = "right";
  floater.appendChild(document.createTextNode("float"));

  document.getElementById("s").appendChild(floater);
}
</script>
</head>

<body onload="boom();">

<span><span id="s"><div></div></span></span>

</body>
</html>