This is very true, and is actually the only time I ever use javascript at all.

I often use javascript in perl functions to validate user input, rather than having my perl script check the inputs.

Something like this ..

print<<CHECK;

<script language="JavaScript">
   if(window.confirm('Really delete $entry?')) {
    location.href=("$0&aktion=Delete&confirm=1");
   }
   else {
    history.back();
   }
</script>    

CHECK
[download]

Then I can check the value of $confirm with a cute little pop up box, and do whatever is needed to, without ever coming back to the server.