ถามเรื่อง ใช้ Javascript ตรวจสอบว่า ห้ามกรอกค่าซ้ำกันเกิน 2 input box ค่ะ

<script language="javascript">
function fncCheck(){
	var _txt = "";_score = "";_split = ""
	var _chk = 0;_void = false

		for(var i = 1;i<=5;i++){
		_score = document.getElementById("score"+i).value
		_txt += ","+_score
		}

		_split = _txt.split(",")

		for(var i = 1;i<=5;i++){
		    _chk = 0
			_void = false
			_score = document.getElementById("score"+i).value
			for(var j=0;j<_split.length;j++){
			   if(_split[j] == _score){
				_chk += 1
			   }
			}

			if (_chk > 2){
			alert("> 2")
			_void = true
			break;
			}
		}
		
		if (_void == false){
			if(confirm("Are you sure you want to send data ???")){
				document.f.target ="_top";
				document.f.method ="post";
				document.f.action ="filename";
				document.f.submit();
			}
		}
	
}
</script>

<form name="f">
<INPUT TYPE="text" NAME="score1" id="score1">&nbsp;1<br>
<INPUT TYPE="text" NAME="score2" id="score2">&nbsp;2<br>
<INPUT TYPE="text" NAME="score3" id="score3">&nbsp;3<br>
<INPUT TYPE="text" NAME="score4" id="score4">&nbsp;4<br>
<INPUT TYPE="text" NAME="score5" id="score5">&nbsp;5<br>
<input type="button" value="Check" onclick="fncCheck();">
</form>

<script language=Javascript>
      <!--
      function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 49 || charCode > 53))
            return false;

         return true;
      }
      //-->
   </script>


<script language=Javascript>
<!--

function validate_form ( )
{
    valid = true;
    var c1=0
    var c2=0
    var c3=0
    var c4=0
    var c5=0
    len=document.form3.answer.length


        for (i=0;i<=len;i++)    {
           // document.form3.answer[i].value
           if (document.form3.answer[i].value=="")  {
            alert ("กรุณากรอกคะแนนให้ครบ");
            document.form3.answer[i].focus();
            valid = false;
            return valid;
            }

           if (document.form3.answer[i].value==1)  {
                c1=c1+1
                if (c1>4)   {
            alert ("ค่าคะแนน "+document.form3.answer[i].value+" มากกว่าจำนวนที่กำหนด");
            valid = false;
            return valid;
                }
            }
           if (document.form3.answer[i].value==2)  {
                c2=c2+1
                if (c2>4)   {
            alert ("ค่าคะแนน "+document.form3.answer[i].value+" มากกว่าจำนวนที่กำหนด");
            valid = false;
            return valid;
                }
            }
           if (document.form3.answer[i].value==3)  {
                c3=c3+1
                if (c3>4)   {
            alert ("ค่าคะแนน "+document.form3.answer[i].value+" มากกว่าจำนวนที่กำหนด");
            valid = false;
            return valid;
                }
            }
           if (document.form3.answer[i].value==4)  {
                c4=c4+1
                if (c4>4)   {
            alert ("ค่าคะแนน "+document.form3.answer[i].value+" มากกว่าจำนวนที่กำหนด");
            valid = false;
            return valid;
                }
            }
           if (document.form3.answer[i].value==5)  {
                c5=c5+1
                if (c5>4)   {
            alert ("ค่าคะแนน "+document.form3.answer[i].value+" มากกว่าจำนวนที่กำหนด");
            valid = false;
            return valid;
                }
            }
        }

    return valid;
}

//-->
</script>   

ท่านตัดสินคบคนจากอะไร 
<br />ให้กรอกเลข 1,2,3,4,5 ในช่องให้คะแนน โดยใส่ค่าคะแนนห้ามซ้ำกันเกิน 4 ข้อ

<form name=form3 action=form.php method=post  onsubmit="return validate_form ( );">

  <?php 
include "dataconnect.php";
  $sql="SELECT * FROM table ORDER BY id";
  $result=mysql_query($sql,$conn);
echo "<table>";
  while ($row=mysql_fetch_array($result))   {
    $id=$row['id'];

    $desc=$row['desc'];
    $score=$row['score'];

    echo "<tr>";
    echo "<td width=100%>";

    echo "<input type=\"text\" name=\"answer[]\" id=\"answer\" value=$score maxlength=1 onkeypress=\"return isNumberKey(event)\" style='width:20px;' /> $id. $desc";
    echo "</td>";
    echo "</tr>";

  }
echo "<tr><td><input type=\"submit\" value=\"ส่งค่า\" />"</td></tr>";
echo "</table>";
  ?>
</form>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></script>
<script type="text/javascript">
	function check_value(selector){
	
		 if($(selector).val() != ''){
			var num = 0;
			$('input[name^="score"]').each(function(){
				if( $(this).val() == $(selector).val() ){
					num = num + 1;
				}
			});
			if(num > 2){
				alert('เกินไปล่ะ!');
				$(selector).val('');
				$(selector).focus();
			}
		 }
		 
	}
</script>
<title>Untitled Document</title>
</head>

<body>
<form name="f">
<INPUT TYPE="text" NAME="score1" id="score1" onkeyup="check_value('#score1');" >&nbsp;1<br>
<INPUT TYPE="text" NAME="score2" id="score2" onkeyup="check_value('#score2');" >&nbsp;2<br>
<INPUT TYPE="text" NAME="score3" id="score3" onkeyup="check_value('#score3');" >&nbsp;3<br>
<INPUT TYPE="text" NAME="score4" id="score4" onkeyup="check_value('#score4');" >&nbsp;4<br>
<INPUT TYPE="text" NAME="score5" id="score5" onkeyup="check_value('#score5');" >&nbsp;5<br>
<input type="button" value="Check" onclick="fncCheck();">
</form>
</body>
</html>