A reference to the Window object that opened this one, or null if this window was opened by the user.
If the current window is a frame, a reference to the frame of the window that contains it.
A self-referential property; a reference to the current Window object. A synonym for window.
If the current window is a frame, a reference to the Window object of the top-level window that contains the frame. Note that top is different from parent for frames nested within other frames.
First step,search the web.
The last,go to a forum and post a new thread for your question.