function checkFields() {
missinginfo = "";
if (document.kontak.nama.value == "") {
missinginfo += "\n     +)  Name";
}
if ((document.kontak.email.value == "") || 
(document.kontak.email.value.indexOf('@') == -1) || 
(document.kontak.email.value.indexOf('.') == -1)) {
missinginfo += "\n     +)  Email address";
}
if(document.kontak.subjek.value == "") {
missinginfo += "\n     +)  Subject";
}
if(document.kontak.pesan.value == "") {
missinginfo += "\n     +)  Message";
}

if (missinginfo != "") {
missinginfo ="_____________________________\n" +
"You failed to correctly fill in your:\n" +
missinginfo + "\n_____________________________" +
"\nPlease re-enter and submit again!";
alert(missinginfo);
return false;
}
else return true;
}