function ck(){
var UserName=document.reg.UserName.value;
var Pwd=document.reg.Pwd.value;
var cPwd=document.reg.cPwd.value;
var RealName=document.reg.RealName.value;
var Sex=document.reg.Sex.value;
var BirthYear=document.reg.BirthYear.value;
var BirthMonth=document.reg.BirthMonth.value;
var BirthDay=document.reg.BirthDay.value;
var Loc=document.reg.Loc.value;
var Addr=document.reg.Addr.value;
var PostCode=document.reg.PostCode.value;
var Tel=document.reg.Tel.value;
var Email=document.reg.Email.value;

if (IsBufferEmpty(UserName,"请填写你的用户名 !"))
{
 document.reg.UserName.value="";
 document.reg.UserName.focus();
 return false;  
}
if (UserName.length < 5 || UserName.length > 16)
{
 alert("用户名长度应在(5-16)之间");
 document.reg.UserName.value="";
 document.reg.UserName.focus();
 return false;
}

if (IsBufferEmpty(Pwd,"请填写你的密码 !"))
{
 document.reg.Pwd.value="";
 document.reg.Pwd.focus();
 return false;  
}
if (Pwd.length < 5 || Pwd.length > 16)
{
 alert("密码长度应在(5-16)之间");
 document.reg.Pwd.value="";
 document.reg.Pwd.focus();
 return false;
}

if (IsBufferEmpty(cPwd,"请验证你的密码 !"))
{
 document.reg.cPwd.value="";
 document.reg.cPwd.focus();
 return false;  
}

if (Pwd!=cPwd){
 alert("请验证你的密码是否正确！");
 document.reg.Pwd.value="";
 document.reg.cPwd.value="";
 document.reg.Pwd.focus();
 return false;
}

if(RealName=="" || Sex=="" || BirthYear=="" || BirthMonth=="" || BirthDay=="" || Loc=="" || Addr=="" || PostCode=="" || Tel=="" || Email==""){
 alert("请填写带*号的资料！");	
 return false;
}

if ( !isemail(Email) ){
 return false;}
}


<!-- Custom Function -->
function IsBufferEmpty(buffer,warnStr){
if (buffer.length==0){
if (warnStr.length>0) alert(warnStr);return true;}
var i=0;
var ret=true;
while (i < buffer.length){
temp=buffer.substring(i,i+1);
if (temp=='\\' || temp=='/' || temp==':' || temp=='*' || temp=='?' || temp=='&' ||
temp=='"' || temp=='<' || temp=='>' || temp=='|' || temp=='\''){
alert('用户名,密码不可包括\\/:*?"<>|\'&');return true;}
if (ret==true && temp!=' ')
ret=false;
i=i+1;}
if (ret && warnStr.length>0)
alert(warnStr);
return ret;}

function isemail (s){
 if (s.length > 100){
   window.alert("email地址长度不能超过100位!");
   return false;}
 var regu = "^(([0-9a-zA-Z]+)|([0-9a-zA-Z]+[_.0-9a-zA-Z-]*[0-9a-zA-Z]+))@([a-zA-Z0-9-]+[.])+([a-zA-Z]{2}|net|NET|com|COM|gov|GOV|mil|MIL|org|ORG|edu|EDU|int|INT)$"
 var re = new RegExp(regu);
 if (s.search(re) != -1) {
    return true;
    } else {
    window.alert ("请输入有效合法的E-mail地址 ！")
    return false;
}}