Selected Index Change of a Drop Down List

I have I one drop down list and one textbox contol on my asp page.
I want to do that, when I changed the selected index of a drop down list with special condition the textbox become disabled.
For example;
Private Sub ddlCalismaDurumu_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles       ddlCalismaDurumu.SelectedIndexChanged
        If ddlCalismaDurumu.SelectedIndex = 1 Then
            txtSure.Enabled = False
        End If
    End Sub
But this solution does not work. Because (I think) it requires refresh.
So how can I do that without refresh.
Many Thanks
Who is Participating?
Ramesh SrinivasConnect With a Mentor Technical ConsultantCommented:
Check that the DropDownLists control has the option "AutoPostBack" is set to True.


u can do it with java script
<asp:DropDownList id="DropDownList1" runat="server" onChange="javascript:dropDownUpdate1();"></asp:DropDownList>

then add this function in the javascript section
function dropDownUpdate1() {
      if document.getElementById("dropdownlist1").value =1
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Can you use javascript for this solution or do you have to post back and disable the button on the server?

Does the solution have to be compatible for all browsers, or can it work just on IE?

WHERE are you adding or binding date with dropdown list. if you binding data from any database then call the binding data like this in page onload event

if page.ispostback = false then

also set autopost back property of list box to true

i think your are not getting the selected index of of the list box. try to debug your code



Check the "AutoPostBack" property for the DropDownList and set it to "True".
A selection change in a DropDownList does not cause a postback by default, that is why the SelectedIndexChanged event does not fire. A refresh sort-of simulates a postback and the event fires.

Set the "AutoPostBack=True" and you won't need to refresh.
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