Show (Display) Sweet Alert Message from Server Side in ASP.Net using C# and VB.Net

Hi paulrajmca,

I have checked. Your code is working.

Refer below code.

HTML

<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/1.8.3/jquery.min.js"></script>
<script type="text/javascript" src="https://unpkg.com/sweetalert/dist/sweetalert.min.js"></script>
<asp:Button ID="btnShow" Text="Show" runat="server" OnClick="OnShow" />

Code

C#

protected void OnShow(object sender, EventArgs e)
{
    ErrorMessage(this, "Welcome", "Greeting");
}

public void ErrorMessage(UI.Control Control, string Message, string Title = "Alert", string callback = "")
{
    try
    {
        ScriptManager.RegisterStartupScript(Control, Control.GetType, "Script", "swal('" + Title + "','" + Message + "','error');", true);
    }
    catch (Exception ex)
    {
    }
}

VB.Net

Protected Sub OnShow(sender As Object, e As EventArgs)
    ErrorMessage(Me, "Welcome", "Greeting")
End Sub

Public Sub ErrorMessage(ByVal Control As UI.Control, ByVal Message As String, Optional ByVal Title As String = "Alert", Optional ByVal callback As String = "")
    Try
        ScriptManager.RegisterStartupScript(Control, Control.GetType, "Script", "swal('" + Title + "','" + Message + "','error');", True)
    Catch ex As Exception
    End Try
End Sub

Screenshot