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The kind of thing you're asking is best managed by a content-management system, and as Rambo Tribble has said, because Javascript is client-side, there is no reliable way of protecting the source. I also know of no existing Javascript menu system which is easily editable in the way you require.
There are loads of CMSs available. Considering your nickname, might I suggest you have a look at the excellent (and free) Mambo Server [mamboserver.com]! ;)