Multi Line TextBox Max Length not Working?

please try this

<asp:textbox id="txtValue" runat="server" textmode="MultiLine" rows="10" columns="50">

$(document).ready(function(){
var MaxLength = 250;
$('#txtValue').keypress(function(e)
{
if ($(this).val().length >= MaxLength)
{
e.preventDefault();
}
});});

i hope this helps you !!!!

Try this:
HTML:

<asp:textbox rows="5" columns="80" id="txtCommentsForSearch" maxlength="1999" onkeydown="checkTextAreaMaxLength(this,'2000');" textmode="multiLine" runat="server" xmlns:asp="#unknown"> </asp:textbox>

Javascript:

function checkTextAreaMaxLength(textBox,e, length)
{
    var mLen = textBox["MaxLength"];
    if(null==mLen)
        mLen=length;
    var maxLength = parseInt(mLen);
     if(textBox.value.length > maxLength-1)
     {
        if(window.event)//IE
            e.returnValue = false;
        else//Firefox
            e.preventDefault();
     }
}

--Amit

<asp:TextBox runat="server" TextMode="MultiLine" ID="txt1" onkeyup="checkLength();" />
        <script type="text/javascript">
            function checkLength() {
                var sender = document.getElementById('<%=txt1.ClientID %>');
                if (sender.value.length > 10) {
                    sender.value = sender.value.substr(0, 10);
                }
            }
        </script>

Try these code which is much better and reliable which i got from http://stackoverflow.com/questions/1334286/specifying-maxlength-for-multiline-textbox [^] posted by Alex Angas.

<asp:regularexpressionvalidator runat="server" id="valInput" xmlns:asp="#unknown">
    ControlToValidate="txtInput"
    ValidationExpression="^[\s\S]{0,100}$"
    ErrorMessage="Please enter a maximum of 100 characters"
    Display="Dynamic">*</asp:regularexpressionvalidator>

Hello,

<asp:textbox id="txt" runat="server" onkeypress="if (this.value.length > 100) { return false; }" xmlns:asp="#unknown">

its working 100%