hello !
   i want popup a window while closing current window 

To pop-up a new window, you can use the window.open function.  Here's an example:
window.open ("http://www.sql-server-helper.com",
"sqlwindow","menubar=1,resizable=1,width=350,height=250");
Then to close the current window, just call window.close();
Regards,
SQL Server Helper

I think you could close the current window using self.close as this:-
<A href="javascript: self.close()">Close this Window</A>
And, open a new one using window.open("  "). Use it in a function like this:-
<SCRIPT language="JavaScript1.2">
function popuponclick()
{
 my_window = window.open("",
    "mywindow","status=1,width=350,height=150");
my_window.document.write('<H1>The Popup Window</H1>');   
} 

Call the pop up window using window.open() method in the onbeforeunload event of the body tag

for open window >>
window.open('http://www.pageresource.com/jscript/jex5.htm','mywindow','width=400,height=200,toolbar=yes, 
location=yes,directories=yes,status=yes,menubar=yes,scrollbars=yes,copyhistory=yes, 
resizable=yes')

For close current window >>
1.) window.close()
2.) self.close()