Wmlscript中判断email的函数

如下：
function IsEmail(s)
{
 var i = 1;
 var sLength = String.length(s);

 if ( sLength <= 1 ) return false ;
 while ((i < sLength) && (String.charAt(s,i) != "@"))
 { i++
 }

 if ((i >= sLength) || (String.charAt(s,i) != "@")) return false;
 else i += 2;

 while ((i < sLength) && (String.charAt(s,i) != "."))
 { i++
 }

 if ((i >= sLength - 1) || (String.charAt(s,i) != ".")) return false;
 else return true;
}

extern function CheckInput()
{
 var ss = WMLBrowser.getVar("MailReceiveAddr");
 if(IsEmail(ss) == true)
 {
  Dialogs.alert("yes");
 }
 else
 {
  Dialogs.alert("no");
 }
}