function checkFields() {
missinginfo = "";

if (document.emailFriend.yourName.value == "") {
missinginfo += "\n     - Name";
}
if (document.emailFriend.friendName.value == "") {
missinginfo += "\n     - Friend's name";
}
if (!validateEmail(document.emailFriend.emailAddr.value)) {
missinginfo += "\n     - Friend's email address";
}

if (missinginfo != "") {
missinginfo ="_____________________________\n" +
"Ooops, you forgot to fill in your:\n" +
missinginfo + "\n_____________________________" +
"\nPlease re-enter and submit again!";
alert(missinginfo);
return false;
}
else return true;
}
//  End -->
<!--http://www.devarticles.com/c/a/JavaScript/Regular-expressions-in-JavaScript/8/-->
function validateEmail ( email ) {
 emailRe = /^[a-zA-Z_0-9-'\+~]+(\.[a-zA-Z_0-9-'\+~]+)*@([a-zA-Z_0-9-]+\.)+[a-zA-Z]{2,7}$/;
 if( !emailRe.test( email ) ) {
  return false;
 }
 return true;
}

//  End -->