You can't.

 

In SSJS you can use the print("") function to output information to the server console. If you want to send an alert() to a browser user, you need to use clientside javascript.

 

(you can of course show the clientside alert conditionally based on a serverside variable)

 

Mark

 

You can use the XSP messaging system with the extended @Functions provided by the Extension Library:

 

@ErrorMessage

@InfoMessage

@WarningMessage

 

/Newbs

What I did was to use the extension library dialog box.

 

I was unable to get @ErrorMessage or any of the other suggested functions to work.   As typical it isn't documented anywhere.