输入字数提示文本框

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

   


   

   
       
           
       
       
           
       
   

               
                                    ReadOnly="True">0

                                    BorderWidth="1px" Height="125px" MaxLength="2000" Width="350px">

   

 

 

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        txtCount.Text = txtInput.MaxLength.ToString();
        txtInput.Attributes.Add("onKeyUp","javascript:document.getElementById('" +txtCount.ClientID+"').setAttribute('value',("+txtInput.MaxLength+" -  parseInt(document.getElementById('"+txtInput.ClientID+"').getAttribute('value').length)));");

    }
    public int MaxLength
    {
        get { return txtInput.MaxLength; }
        set { txtInput.MaxLength = value; }
    }
   
}