JS e-mail QQ number MSN Verification code

Email email Verification

if (document.regform.u_email.value.length==0) {
Alert ("Hint: please fill in your email address");
Document.regform.u_email.focus ();
return false;
}

else if ((Document.regform.u_email.value.indexof ("@") <0) | | (Document.regform.u_email.value.indexof (":")!=-1))
{
Alert ("Hint: you fill out the email is invalid, please fill in a valid email");
Document.regform.u_email.focus ();
return false;
}

QQ Number Verification Code
if (document.regform.u_qq.value.length!=0) {

if (!checkifnumber (Document.regform.u_qq.value)) {
Alert ("Hint: QQ number format Error!") ");
Document.regform.u_qq.focus ();
return false;
}
} 

MSN Authentication Code

     if (document.regform.u_msn.value.length!=0) {
           if ((Document.regform.u_msn.value.indexof ("@") <0) | | (Document.regform.u_msn.value.indexof (":")!=-1))
                {
                          alert ("Hint: You fill out the MSN is invalid, please fill out a valid MSN");
                         Document.regform.u_msn.focus ();
                         return false;
               }
 }
}