<!DOCTYPE html>
<html>
<script>

function boom()
{
  var textareaRoot = document.createElement("textarea");
  document.removeChild(document.documentElement);
  document.appendChild(textareaRoot);
  var input = document.createElement("input");
  textareaRoot.appendChild(input);
  input.select();
}

</script>
</head>
<body onload="boom();"></body>
</html>