// JavaScript Document
<!-- hide script from non-Java browsers
//Ham kiem tra dia chi Email hop le
   function isEmail(s) {
       if (s == "") return false;
       if(s.indexOf(" ") > 0) return false;
       var i = 1;
       var sLength = s.length;
       if (s.indexOf(".") == sLength) return false;
       if (s.indexOf(".") <= 0) return false;
       if (s.indexOf("@") != s.lastIndexOf("@")) return false;
       while ((i < sLength) && (s.charAt(i) != "@"))  { i++  }
       if ((i >= sLength) || (s.charAt(i) != "@")) return false;
       else i += 2;
       while ((i < sLength) && (s.charAt(i) != "."))  { i++  }
       if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
       var str="1234567890abcdefghikjlmnopqrstuvwxyz-@._";
       for(var j=0; j<s.length; j++)
           if(str.indexOf(s.charAt(j)) == -1)
               return false;
       return true;
   }

//Ham kiem tra tinh hop le cua du lieu khi nhan Submit
   function checkInput(){
	   if(document.frm_send.user_name.value == ""){
           alert("Please enter Your Full Name !");
           document.frm_send.user_name.focus();
           return false;
	   }
       if (document.frm_send.user_email.value == "") {
           alert("Please enter Your own Email !");
           document.frm_send.user_email.focus();
           return false;
       }
       if (!isEmail(document.frm_send.user_email.value)) {
           alert("Invalid Email, Please enter Your own Email !");
           document.frm_send.user_email.focus();
           return false;
       }
	   if(document.frm_send.subject.value == ""){
           alert("Please enter Your Subject !");
           document.frm_send.subject.focus();
           return false;
	   }
	   if(document.frm_send.confirm_code.value == ""){
           alert("Please enter the code !");
           document.frm_send.confirm_code.focus();
           return false;
	   }
       if (document.frm_send.txt_comment.value == "") {
           alert("Please enter Your comments and special instruction !");
           document.frm_send.txt_comment.focus();
           return false;
       }
       return true;
   }
   
//Ham kiem tra va gioi han ky tu
   var szMaxStr  = new String();
   var nMaxDesc = new Number(5000);//Gioi han chuoi ky tu
   
   function CountCharacters(){
       var szStr = new String(frm_send.txt_comment.value );
       frm_send.CharCnt.value = szStr.length;
       if(szMaxStr.length){
           if(szStr.length > (nMaxDesc))
               frm_send.txt_comment.value = szMaxStr;
           else
               szMaxStr = frm_send.txt_comment.value;
       }else{
           if(szStr.length > (nMaxDesc)){
               alert("Your comments exceeds " + nMaxDesc + " Characters.  Please shorten it");
               szMaxStr = frm_send.txt_comment.value;
               szMaxStr = szMaxStr.substring(0,nMaxDesc);
               frm_send.txt_comment.value = szMaxStr;
               frm_send.txt_comment.select();
           }
       }
   }
// End the hiding here. -->