จากโค๊ดด้านล่าง ผมอยากใช้จาวาสคริปตรวจสอบช่องจำนวนที่เบิกไม่ให้ผู้ใช้ป้อนมากกว่าจำนวนคงเหลือครับ อยากให้พี่ๆช่วยแนะนำหน่อยครับ(มือใหม่ครับ)

<?
		session_start();
		
		if($_SESSION['per_id'] == "")  
		{
			$errorMessage = "Please Login !";        
			include ("page-fragment/login/LoginForm.php");     
			exit();    
		} 
		
		include_once("function/DatabaseSetting.php");	
		
		mysql_connect(DB_SERVER,DB_USERNAME,DB_PASSWORD);
		mysql_select_db(DB_DATABASE_NAME);
		$strSQL = "SELECT * FROM person p
				   JOIN department s ON p.depart_id=s.depart_id
				   WHERE per_id = '".$_SESSION['per_id']."' ";
		
		$objQuery = mysql_query($strSQL);
		$objResult = mysql_fetch_array($objQuery);
	?> 
      
     </br><h1 class="h1">เบิกเวชภัณฑ์</h1>
           	
	<?
		mysql_connect(DB_SERVER,DB_USERNAME,DB_PASSWORD);
		mysql_select_db(DB_DATABASE_NAME);
		$strSQL = "SELECT * FROM unit";
		$objQuery = mysql_query($strSQL);
	?>

<script language="javascript">

	function OpenPopup(intLine)
	{
		window.open('page-fragment/order/OrderPopUpList.php?Line='+intLine,'myPopup','width=650,height=460,toolbar=0, menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');
	}

	function CreateNewRow()
	{
		var intLine = parseInt(document.frmMain.hdnMaxLine.value);
		intLine++;
			
		var theTable = document.getElementById("tbExp");
		var newRow = theTable.insertRow(theTable.rows.length)
		newRow.id = newRow.uniqueID

		var newCell
		
		//*** Column No ***//
		newCell = newRow.insertCell(0);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		newCell.innerHTML = "<center>"+intLine+"</center>";

		//*** Column รหัส ***//
		newCell = newRow.insertCell(1);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		newCell.innerHTML = "<center><INPUT TYPE=\"TEXT\" SIZE=\"5\" NAME=\"me_id"+intLine+"\"  ID=\"me_id"+intLine+"\" VALUE=\"\"></center>";

		//*** Column ชือ ***//
		newCell = newRow.insertCell(2);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		newCell.innerHTML = "<center><INPUT TYPE=\"TEXT\" SIZE=\"12\" NAME=\"me_name"+intLine+"\"  ID=\"me_name"+intLine+"\" VALUE=\"\"></center>";

		//*** Column จำนวนคงเหลือ ***//
		newCell = newRow.insertCell(3);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		newCell.innerHTML = "<center><INPUT TYPE=\"TEXT\" SIZE=\"3\" NAME=\"stock"+intLine+"\" ID=\"stock"+intLine+"\" VALUE=\"\"></center>";
		
		//*** Column หน่วย ***//
		newCell = newRow.insertCell(4);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		newCell.innerHTML = "<center><INPUT TYPE=\"TEXT\" SIZE=\"5\" NAME=\"unit_id"+intLine+"\" ID=\"unit_id"+intLine+"\" VALUE=\"\"></center>";

		//*** Column จำนวนที่เบิก ***//
		newCell = newRow.insertCell(5);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		newCell.innerHTML = "<center><INPUT TYPE=\"TEXT\" SIZE=\"5\" onkeyup=\"checkNumeric(this)\" NAME=\"amount"+intLine+"\" ID=\"amount"+intLine+"\" VALUE=\"\"></center>";
				
		//*** Column 7 ***//
		newCell = newRow.insertCell(6);
		newCell.id = newCell.uniqueID;
		newCell.setAttribute("className", "css-name");
		//newCell.setAttribute("OnClick", "OpenPopup('"+intLine+"')");
		newCell.innerHTML = "<center><INPUT TYPE=\"BUTTON\" NAME=\"btnPopup_"+intLine+"\"  ID=\"btnPopup_"+intLine+"\" VALUE=\"...\" OnClick=\"OpenPopup('"+intLine+"')\"></center>";	
	
		document.frmMain.hdnMaxLine.value = intLine;
	}
	
	function RemoveRow()
	{
		intLine = parseInt(document.frmMain.hdnMaxLine.value);
		if(parseInt(intLine) > 0)
		{
				theTable = document.getElementById("tbExp");				
				theTableBody = theTable.tBodies[0];
				theTableBody.deleteRow(intLine);
				intLine--;
				document.frmMain.hdnMaxLine.value = intLine;
		}	
	}
	
	function checkNumeric(obj)
    {
        if ( isNaN(obj.value) )
        {
            alert('กรุณากรอกตัวเลขเท่านั้น..!');
            obj.value = obj.value.substr(0, (obj.value.length) - 1);
            return false;
        }
    }	
</script>
<body OnLoad="CreateNewRow();">
<form name="frmMain" method="post" action="ActionController.php?action=order/CreateOrderAction"> 
										   							  
	<table style="margin-top:-60px">
		<tr>
				<input type="hidden" name="per_id" id="per_id" value="<?=$objResult['per_id']?>" />				
			<td>
				<p>แผนก : </p> 
				<input type="text" name="depart_name" id="depart_name" class="texPay" value="<?=$objResult["depart_name"];?>"/>
			</td>
			<td>
				<p>วันที่เบิก : </p> 
				<input type="text" name="pay_date" id="pay_date" class="texPay" value="<?=date('m-d-Y')?>"/>
			</td>
		</tr>
	</table><br>

<table width="600" border="1" id="tbExp">
  <tr>
    <th><div align="center">ลำดับ</div></th>
    <th><div align="center">รหัสเวชภัณฑ์</div></th>
    <th><div align="center">ชื่อเวชภัณฑ์</div></th>
    <th><div align="center">คงเหลือ</div></th>
    <th><div align="center">หน่วย</div></th>
    <th><div align="center">จำนวนเบิก</div></th>
	<th><div align="center">เลือก</div></th>
  </tr>
</table>
<br><br><br><br>
	<div style="position: relative; left: 45px">
		<input type="hidden" name="hdnMaxLine" value="0">
		<input name="btnAdd" type="button" id="btnAdd" value="+" onClick="CreateNewRow();">
		<input name="btnDel" type="button" id="btnDel" value="-" onClick="RemoveRow();">
		<input type="submit" name="btnSubmit" value="ตกลง">
	</div>
</form>