How can I set the maximum length of a
singleline/multiline textbox in a webform?
Restricting the length of text on a Single line/Multi line textbox is not
supported by the standard ASP.NET Web control. This can be done by adding the
following Javascript function in your ASPX page.
1. Add a javascript
At the top of your ASPX page you will see the following tag . Add the following
code under this tag:
function
Count(text,long)
{
var maxlength = new Number(long);
// Change number to your max
length.
if (text.value.length > maxlength){
text.value =
text.value.substring(0,maxlength);
alert("
Only " + long + " characters");
}
2. Change your text controls on your ASPX page
On every multi-line text box where you would like to control the length, add the
following code to the asp text box control.
onKeyUp="Count(this,300)" onChange="Count(this,300)"
Your original text control before adding this code:
<asp:TextBox
ID="TESTDATA"
runat="server"
TextMode="MultiLine">asp:TextBox>
After adding the code:
<asp:TextBox
ID="TextBox1"
runat="server"
onKeyUp="Count(this,300)"
onChange="Count(this,300)"
TextMode="MultiLine">asp:TextBox>