This article is used to show message window in vb.net using ajax. The problem comes when you use vb.net using ajax enables website.. This concept is easy to use in C# but it is not easy in vb.net. I am writing two line code for this message window.
Private Sub DisplayClientError(ByVal errorDesc As String)
Dim script As String = "alert('" + errorDesc + "');"
ScriptManager.RegisterStartupScript(Me, GetType(Page), "UserSecurity", script, True)
End Sub 'DisplayClientError write this code on click event where you want show message window
Protected Sub ClickButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles ClickButton.Click
If TextBox1.Text = "" Then
DisplayClientError("Enter some text in text box")
End If
End Sub
Screen Shot