<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script>
$(document).ready(function () {
//Listen
for a key up event on the search input
$('#txt_search').keyup(function () {
//When a user presses and releases a key
//Check to see if the length of the inputted
//data
is greater than 2
if ($(this).val().length > 2) {
//If the input length is greater than
//two then we enable the search button
$('#btn_search').prop("disabled", false);
} else {
//If the input length is equal to 2 or less we disable the
search button
$('#btn_search').prop("disabled", true);
}
});
});
</script>
<asp:TextBox ID="txt_search" runat="server"></asp:TextBox>
<asp:Button ID="btn_search" runat="server" Text="Search" disabled />
<asp:TextBox ID="txt_search" runat="server"></asp:TextBox>
<asp:Button ID="btn_search" runat="server" Text="Search" disabled />