TextBox TextChange event is not working in vb.net - asp.net

Question

I am using asp textbox control with TextChange event, trying to set the text to label as the textbox text get changed but it is working when i loose the focus from textbox not when text changes.
the problem with loosing focus is that if i use AutoPostBack="true" it refresh the page which affects my other values...
my source for textbox on aspx page
<asp:TextBox ID="txtSearchCust" runat="server" Width = "200" OnTextChanged="txtSearchCust_TextChanged" AutoPostBack="true" />
my code behind page source
Protected Sub txtSearchCust_TextChanged(sender As Object, e As EventArgs) Handles txtSearchCust.TextChanged
QtyChk.Text=txtSearchCust.Text
End Sub
here QtyChk is the label where I am trying to set the text
any solution...?

Answer 1

Based on your question.
<script type="text/javascript">
function doTextBoxChange() {
__doPostBack();
}
</script>
<asp:TextBox ID="TextBox1" runat="server" AutoPostBack="True" onkeydown="return doTextBoxChange();"></asp:TextBox>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If IsPostBack() Then
LabelChange()
End If
End Sub
Sub LabelChange()
Label1.Text = "1234"
End Sub
But I think use javascript is a better option.
The values will disappear after post, you need to request the value and setup.
otherwise, use viewstate or session.
Using the javascript, don't post form data.
<form id="form1" runat="server">
<div>
<asp:TextBox ID="TextBox1" runat="server" onkeyup="return doTextBoxChange();"></asp:TextBox>
<asp:Label ID="Label1" runat="server" Text=""></asp:Label>
</div>
</form>
function doTextBoxChange() {
var inputValue = document.getElementById("TextBox1").value;
document.getElementById('<%= Label1.ClientID %>').innerHTML = inputValue;
}