Delete all pages except currently viewed?? Acrobat Javascript

Hello All,

I need to delete all pages in a PDF except the one that is currently being viewed. I thought I had it with this:

var keepPage=this.pageNum
this.deletePages({nStart: keepPage+1, nEnd: this.numPages -1});
var keepPage=this.pageNum
this.deletePages({nEnd: keepPage -1});

But this only works if you are on a page other than the last page.

I appreciate any help.