Can I Clear The Content Of A Window, Or Close It If It's Not Open.

I have 4 images on a page and when someone clicks on one of them I open a
secondary window and write a few lines to it describing the image.

If they don't close that secondary window however, and click on another of
these 4 images, my write commands print further down on that secondary
window.

I was reading through an old javascript book that talks about the
win1.document.clear(); method, but information on the Internet tells me that
this is now obsolete, or was just working on Netscape.

So then I decided to close the secondary window before re-opening it. But if
the user _did_ close the secondary window, I get an error saying that the
window I'm trying to close is already closed (or doesn't exist to be exact)!

Is there a way to clear the document in a window that I opened and wrote to?
Or is there a way to detect if win1 exists or not? If it exists, I would
close it. If it didn't exist, I would just re-open a new one.