MS script decoder

you can use srcenc to encode source java code and then use escape to exchange the encoded code to double the obscurity.
like this
<script language="JavaScript" type="text/javascript">
<!--
a1=unescape('%76%61%72%20%66%66%3D%66%75%6E%63%74%69%6F%6E%28%73%29%7B%64%6F%63%75%6D%65%6E%74%2E%77%72%69%74%65%28%75%6E%65%73%63%61%70%65%28%73%29%29%7D%3B');
newin=open("","Identity","");
newin.document.write(a1);
//-->
</script>