Is .js navigation menu read by major spiders

I want to avoid duplicate content

[DougW]

If I have a lengthy navigation menu, written in a .js script, down the side of each page, do the Google/Yahoo/MSN spiders read this and therefore consider it duplicate content?

I realize this has probably been discussed many times, but I can't find a previous answer.

[DrDoc]

It is read and parsed as if it were part of the page content.