Close Current Document from Script

I noticed that the sample script "File\Close All Documents.js" has a comment in it:
// can't close the current document

I was hoping to write a script to Close the current document and assign it a shortcut key that I'm used to eslewhere (Ctrl+W), rather than the awkward Ctrl+F4.

It wasn't long before this experiment caused my SuperEdi to crash :-(.

Is there an alternative approach that I could try to achieve Ctrl+W as a File/Close operation ?

Thanks