[Javascript] How to decode obfuscated Javscript

[SkyScanner]

Does anyone know how to decode obfuscated Javscript, or view a script 'as 
the browser is seeing it' ???

I have a page here:
http://www.mapability.com/obfuscator.htm
(please view the source) that has an obfuscated script in it. I need very 
much to view this script and be able to change it. Unfortunately, the site 
that I obtained the script from, many years ago, (StickySauce) has closed 
down and disappeared, so I have no way of contacting the original author.

Can anyone help?

Tim ,was in Ireland, now in England
www.mapability.com/travel

PS - if YOU need a good obfuscator, I would recommend this page. Save it to 
your computer and use it off-line.