Set dropdown text selected from textbox value

In some cases we need to set dropdown list items exact text by matching the value entered in textbox. For that purpose we can use .keyup event in jQuery. In .keyup event simply take the value of textbox and assign that value to the value of dropdown. Once you set value it's corresponding text will be get displayed as selected.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<html xmlns="">
<head id="Head1" runat="server">
    <script src="Scripts/jquery-1.4.1.js" type="text/javascript"></script>
     <script src="Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>
    <title>Get dropdown value</title>
    <script type="text/javascript">
        $(document).ready(function () {
            $("#topics").keyup(function () {
                var value = $("#topics").val();
                if (value == "" || isNaN(value))
                    value = 0;
    <form id="form1" runat="server">
    <asp:TextBox runat="server" ID="topics"></asp:TextBox>
      <asp:DropDownList ID="topics1" runat="server">
     <asp:ListItem Text="--Select--" Value="0"></asp:ListItem>
    <asp:ListItem Text="C#" Value="1"></asp:ListItem>
    <asp:ListItem Text="jQuery" Value="2"></asp:ListItem>
    <asp:ListItem Text="ASP.NET" Value="3"></asp:ListItem>

Note: You may need some additional validations if user enters data in textbox that does not match to the values in dropdown. Ex. I have just validated in above code if user enters characters other than number using IsNaN