Automatically change DropDownList selected item on every 30 seconds using JavaScript in ASP.Net

Hi PRA,

Check this example. Now please take its reference and correct your code.

HTML

<script type="text/javascript" language="javascript">
    window.onload = function () {
        var dropDownOptions = document.getElementById('drpList');
        var counter = 1;
        setInterval(function () {
            document.getElementById('drpList')[counter].selected = true;
            document.getElementById('Label1').innerHTML = dropDownOptions[counter].text;
            counter++;
            if (counter == dropDownOptions.length) {
                counter = 0;
            }
        }, 2000); // Change 2000 with 30000 for 30 secs.
    };
</script>
<asp:DropDownList ID="drpList" runat="server" OnSelectedIndexChanged="drpList_SelectedIndexChanged"
    AutoPostBack="True">
</asp:DropDownList>
<br />
<asp:Label ID="Label1" runat="server"></asp:Label>

Code

C#

protected void Page_Init(object sender, EventArgs e)
{
    System.Data.DataTable dt = new System.Data.DataTable();
    dt.Columns.Add("OptionValue");
    dt.Columns.Add("OptionText");
    dt.Rows.Add("0", "Cars");
    dt.Rows.Add("1", "Animals");
    dt.Rows.Add("2", "Cumputers");
    dt.Rows.Add("3", "Televisions");
    dt.Rows.Add("4", "Oceans");
    drpList.DataSource = dt;
    drpList.DataTextField = "OptionText";
    drpList.DataValueField = "OptionValue";
    drpList.DataBind();
}

protected void drpList_SelectedIndexChanged(object sender, EventArgs e)
{
    Label1.Text = drpList.SelectedItem.Text;
}

VB.Net

Protected Sub Page_Init(ByVal sender As Object, ByVal e As EventArgs)
    Dim dt As System.Data.DataTable = New System.Data.DataTable()
    dt.Columns.Add("OptionValue")
    dt.Columns.Add("OptionText")
    dt.Rows.Add("0", "Cars")
    dt.Rows.Add("1", "Animals")
    dt.Rows.Add("2", "Cumputers")
    dt.Rows.Add("3", "Televisions")
    dt.Rows.Add("4", "Oceans")
    drpList.DataSource = dt
    drpList.DataTextField = "OptionText"
    drpList.DataValueField = "OptionValue"
    drpList.DataBind()
End Sub

Protected Sub drpList_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
    Label1.Text = drpList.SelectedItem.Text
End Sub

Screenshot