I'm sure I've seen some javascript code around somewhere (but I can't find it now!) which
a) detects if a page is being framed by another, and
b) breaks out of that frame.

In other words, I want to make sure that a particular web page of mine is not allowed to be displayed inside a frame on someone else's site (whenever and wherever that might occur).

Can anyone point me to this code?

Thanks very much.