Sarah,
Its a security thing. It'll work without asking if there is only one location in the browsers history, if there's more than one, it prompts the user for confirmation. If this becomes a problem, you can always restrict the history of a window to one location by using the replace() method.
>I avoid JavaScript where possible in favour of serverside but sometimes you just need it!
>
>so I have a button which I want to close a popup "thanks, I've done it"-type of window. Problem is window.close() gives me an alert saying are you sure. Yet when I see the same code used on other sites it doesn't.
>
>I'm wondering if it's something to do with code like window.opener...?
>
>Sarah