is different - they wrote that and know it's parameters. Yes they can tell if it has been altered.
> read js
Not that we know of on an ongoing basis.
> can they read urls in js
yes if they are bare http's, but not if they are interpreted or variablized. (the js is NOT executed that we know of, but many expect that to change any day now).
> i am having 4 codes given by phpadsnew to run ads on
> my website and wanted to was this hurting my seo.
dunno what that is about as it relates to the first q, but if you are manipulating your adsense code - it will get flagged. Basically, you will get booted or your ctr will mysteriously drop. Many of the recent drops in ctr's can be attributed to js code being changed. But that is a q for the adsense forum.