Removing obfuscation before modifying script?

[mono3]

If code in a web page looks like this for 200k (one long line):

Code:

<script type="text/javascript">document.write(String.fromCharCode(parseInt(0x3c)));document.write(String.fromCharCode(parseInt(0x73)));document.write(String.fromCharCode(parseInt(0x63)));         .... </script>

Is there a filter I can activate that undoes that obfuscation and lets me modify the unobfuscated result to prevent popups/divs/iframes?

IE9 if it matters.