Asp.net_实时显示文本框字数

1. <script language="javascript" type="text/javascript"> 
2.         function countNum() 
3.         { 
4.             var count=document.getElementById("txtText").value.length; 
5.             document.getElementById("lblCount").value=count; 
6.             } 
7.     </script> 

<script language="javascript" type="text/javascript">        function countNum()        {            var count=document.getElementById("txtText").value.length;            document.getElementById("lblCount").value=count;            }    </script>

[csharp] view plaincopyprint?

1. <asp:TextBox ID="txtText" name="txtText" runat="server" Columns="80" Rows="8" TextMode="MultiLine" 
2.    Width="650px" Height="150px" onkeydown="countNum();"  
3. onmousemove="countNum();" onmouseout="countNum();" onkeyup="countNum();"></asp:TextBox> 
4.   （已输入<input id="lblCount" type="button" style="border-style: none; background: none;" value="0" />字）