Get previous URL when the user comes from a Bookmark?

I want to make a bookmark, with a pseudo share-it functionality. It would redirect the user to a website and on there I would need the URL the user was when he clicked on my bookmark.

I've read many questions regarding the subject but it seems that is difficult if not impossible to get the previous URL if the user wasn't referred by other page.

Is it possible to do it?

Thanks

Solution

Make a bookmark like this:

javascript:location='http://www.example.com/?ref='+escape(location.href);

A common way to make this work for the user is making a link as the following:

<a href="javascript:location='http://www.example.com/?ref='+escape(location.href);"
 onclick="alert('Drag this link to your boomarks toolbar');return false;">
  Bookmark text
</a>