You can set the
AutoPostBack property to
True just like this:
AutoPostBack="True"
Will going to work better if you put the textbox inside an updatepanel from AJAX =)
In your html code:
<body>
<form id="form1" runat="server" method="post" autocomplete="off">
<div>
<asp:TextBox ID="TextBox1" runat="server" AutoPostBack="True"
ontextchanged="TextBox1_TextChanged">
</div>
<asp:Label ID="Label1" runat="server" Text="Label">
<asp:Button ID="Button1" runat="server" Text="Button" />
</form>
</body>
Hope it helps.