How doI go 'back' on a relative site?

[Bucky]

I am building a relative site and I want to go back a level. How do I put
this on my button?

index[home]/folder 1 ** I would be in 'folder' 1 and I want to go back to
'home' [basically up one level] How do I do this?

[**note- index wouldn't be the root, but rather an index page nested a few
fodlers down**]

[Airnine]

I think this is done through javascript and it's basically a browser thing, it's something like:

history.back()

or something like that