Populate TextBoxes one by one with delay using C# and VB.Net in ASP.Net

Hi taruni,

Refer below code.

HTML

<asp:Button runat="server" ID="btnsupportform" Text="Go Support" OnClick="btnsupportform_Click"
    Style="color: #ffffff; font-size: 14px; margin-left: 20px; cursor: pointer; padding: 8px; background-color: #f39c12; border-radius: 8px;" />
<div class="form-group">
    <div class="col-sm-9">
        <input type="text" class="form-control" id="textBox1" runat="server" />
    </div>
</div>
<div class="form-group">
    <div class="col-sm-9">
        <input type="text" class="form-control" id="textBox2" runat="server" />
    </div>
</div>
<div class="form-group">
    <div class="col-sm-9">
        <input type="text" class="form-control" id="textBox3" runat="server" />
    </div>
</div>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript">
    function PopulateTextBox() {
        $('#textBox1').val('');
        $('#textBox2').val('');
        $('#textBox3').val('');
        setTimeout(function () {
            $('#textBox1').val('HELLO');
            setTimeout(function () {
                $('#textBox2').val('HELLO 1');
                setTimeout(function () {
                    $('#textBox3').val('HELLO 2');
                }, 2000);
            }, 2000);
        }, 2000);
    }
</script>

Code

C#

protected void btnsupportform_Click(object sender, EventArgs e)
{
    string script = "window.onload = function() { PopulateTextBox(); };";
    ClientScript.RegisterClientScriptBlock(this.GetType(), "", script, true);
}

VB.Net

Protected Sub btnsupportform_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim script As String = "window.onload = function() { PopulateTextBox(); };"
    ClientScript.RegisterClientScriptBlock(Me.GetType(), "", script, True)
End Sub

Screenshot