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

<!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 runat="server">

    <title>无标题页</title>


<script language="javascript" type="text/javascript">

function  editorCheck()

    var textBox1 = document.getElementById("TextBox1").value;

    var n = 8 - textBox1.length;

    if(n < 0)

    {

      document.getElementById("Label1").style.color= "#FF0000";

    } 

    else

    {

      document.getElementById("Label1").style.color= "#008000";

    }

}

 </script>

</head>

<body>

    <form id="form1" runat="server">

 <div>

        <asp:TextBox ID="TextBox1" runat="server" Height="373px" TextMode="MultiLine" Width="429px" onkeyup="editorCheck()"   onpropertychange="javascript:document.getElementById('Label1').innerText='您还可输入 ' + (8 - this.value.length) + ' 个字符'" OnTextChanged="TextBox1_TextChanged"></asp:TextBox>

        <asp:Label ID="Label1" runat="server" Font-Bold="True" Font-Underline="False" ForeColor="#008000"

            Height="31px" Width="326px">您还可输入 8000 个字符</asp:Label>

     <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="检查..." /></div>  

    </form>

</body>

</html>




================================================================


    <div>

        <asp:TextBox ID="TextBox1" runat="server" Height="373px" TextMode="MultiLine" Width="429px"  onpropertychange="javascript:document.getElementById('Label1').innerText='您还可输入 ' + (8 - this.value.length) + ' 个字符'"></asp:TextBox>

        <asp:Label ID="Label1" runat="server" Font-Bold="True" Font-Underline="False" ForeColor="Red"

            Height="31px" Width="326px">您还可输入 8000 个字符</asp:Label></div>  


//********************************************************************  后台。。。



protected void Button1_Click(object sender, EventArgs e)

    {

        if (System.Text.RegularExpressions.Regex.IsMatch(this.Label1.Text, "-"))

        {

            //return true;

            Page.RegisterStartupScript("onclick ", " <script> alert( 'alert!!alert!! '); </script> ");

        }

    }

    protected void TextBox1_TextChanged(object sender, EventArgs e)

    {

        int i = this.TextBox1.Text.Length;

        this.Label1.Text = "您还可输入 " + Convert.ToString(8 - i) + " 个字符";

    }

    protected void Button2_Click(object sender, EventArgs e)

    {

        if (System.Text.RegularExpressions.Regex.IsMatch(this.Label1.Text, "-"))

        {

            Response.Write(this.Label1.Text);

        }


    }