How to set maxlength for multiline TextBox?

Question

When using a MultiLine TextBox (which generates a TextArea) setting the MaxLength property has no effect. What is the best workaround? I'd like to get basic, intended functionality with minimum of ugly javascript etc. Just prevent user from entering more than max number of characters.

Answer 1

If you don't care about older browsers (see supported browsers here),
you can set MaxLength normally like this

<asp:TextBox ID="txt1" runat="server" TextMode="MultiLine" MaxLength="100" />

and force it to be printed out to the HTML

protected void Page_Load(object sender, EventArgs e)
{
  if (!IsPostBack)
    txt1.Attributes.Add("maxlength", txt1.MaxLength.ToString());
}

Answer 2

If you want to let the user know if he exceeded the amount of characters as he writes, you could use a javascript function attached to keypress event. This function would test the length of the input and cancel the character rendering if the maxlenght was reached.

Another option is to use RegularExpressionValidator control to validate the input on submit.

In my opinion, the first option is much more better.

I'm not adding any code since google is full of examples for all tastes, this is a very common task.

Here you have a sample search that might help.

Answer 3

Hey pukipuki you can do as follows:

<asp:TextBox ID="txtValue" runat="server"TextMode="MultiLine" Rows="10"Columns="50"></asp:TextBox>

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

You can see more in this following link: http://jquerybyexample.blogspot.in/2010/10/set-max-length-for-aspnet-multiline.html