function checker() {var complete=true; var open=false;
var email=document.f1.sender_email.value;
var name=document.f1.sender_name.value;
if ((email == "") || (email == null) || (name == "") || (name == null)) 
{complete=false; 
alert("Please enter name and email address");}
else { window.open("confirm.html", "krak", "width=220, height=220");}
return complete;}