文本框字数(输入还剩多少字)

 今天自己在做一个小网站的时候用到这个功能,便把代码贴了下来,代码如下:

<script type="text/javascript" language="javascript">     
    function   textCounter(field,   maxlimit)  
     {     
      if   (document.getElementById(field).value.length   >   maxlimit)   
      {
        document.getElementById(field).value   =   document.getElementById(field).value.substring(0,maxlimit);    
      }  
      else     
      {
        document.getElementById("remLen").value   =   maxlimit   -   document.getElementById(field).value.length; 
      }   
    }     
</script> 

 aspx页面代码:

<form runat="server" id="writemsgtxt">
<table width="100%" border="0" cellspacing="0" cellpadding="0">
                      <tr>
                        <td height="22" align="left">&nbsp;你還可以留言
                          <input readonly type="text" id="remLen" runat="server" size="4" maxlength="3" value="500" class="input1" />
                          字
                        </td>
                      </tr>                            
                      <tr>
                        <td align="left">
                        <asp:TextBox ID="content" runat="server" CssClass="input2" Rows="8" Columns="50" TextMode="MultiLine" onkeyup="textCounter('content',500)"></asp:TextBox>
                        </td>
                      </tr>
</table>
</form>