<!-- 
function verify() {
var themessage = "Je bent verplicht de volgende velden in te vullen: ";
if (document.tt.naam.value=="") {
themessage = themessage + "\n - naam";
}
if (document.tt.email.value=="") {
themessage = themessage + "\n - Email";
}
if (document.tt.telefoon.value=="") {
themessage = themessage + "\n - Telefoon";
}
//alert if fields are empty and cancel form submit
if (themessage == "Je bent verplicht de volgende velden in te vullen: ") {
//document.tt.submit();
return true;
}
else {
alert(themessage);
return false;
  }
}
//-->