Force postback with javascript? *Renewed!*

I would like my textboxes to post after they lose focus. I'm assuming the onblur event can be used with the boxes in code behind, but what's the syntax for forcing a postback?

Found it!

Code:

---

            Dim js As String = "javascript:" & Page.GetPostBackEventReference(Me, "@@@@@buttonPostBack") & ";"
            txtFirstName.Attributes.Add("onblur", js)

---

Haveing textboxes constantly post is very anoying. Is there a way to run a vb.net sub in a onblur event? Or can any of you convert my mess into js?

VB Code:

ibtSaveComp.Attributes.Remove("onClick")
        If txtFirstName.Text <> Nothing And txtLastName.Text <> Nothing And txtGroupName.Text <> Nothing Then
            If IO.File.Exists(AppSettings("CompDir") & txtGroupName.Text & "\" & txtLastName.Text & ", " & (txtFirstName.Text & " " & txtMI.Text).TrimEnd & ".xml") Then
                Page.RegisterClientScriptBlock("DeleteComp", "<script language='javascript'>function DeleteComp(){ return confirm('Are you sure you wish to replace this item');}</script>")
            Else
                Page.RegisterClientScriptBlock("DeleteComp", "<script language='javascript'>function DeleteComp(){return true;}</script>")
            End If
        Else
            Page.RegisterClientScriptBlock("DeleteComp", "<script language='javascript'>function DeleteComp(){return true;}</script>")
        End If
        ibtSaveComp.Attributes.Add("onClick", "return DeleteComp()")
    End Sub

What I'm doing is checking if a file exists at post, so I know to raise a confirm box when the button is clicked.