Control compuesto personalizado

[Bravenap]

Muy buenas. He hecho mi primer control personalizado. Se trata de una caja de texto para introducir un código postal de España y encuentre la provincia a la que pertenece. Os lo dejo por si le sirve a alguien y así de paso le sacáis defectos que los tendrá y a montones.

Un saludo.

Código:

Imports System.ComponentModel
Imports System.Web.UI
Imports System.Web.UI.WebControls

Public Class controlCPProvincia
    : Inherits Control : Implements INamingContainer

    Private _idTxt As String
    Private _cpInicial As String

    Public Property IDTxt() As String
        Get
            Return _idTxt
        End Get
        Set(ByVal Value As String)
            _idTxt = Value
        End Set
    End Property

    Public Property CPInicial() As String
        Get
            Return _cpInicial
        End Get
        Set(ByVal Value As String)
            _cpInicial = Value
        End Set
    End Property

    Protected Overrides Sub CreateChildControls()
        Dim txt As New TextBox
        txt.MaxLength = "5"
        txt.Columns = "1"
        txt.ID = IDTxt
        txt.Text = CPInicial
        Dim lbl As New Label
        lbl.ID = "lbl" & IDTxt
        lbl.Text = "Provincia no identificada"
        'Script con vectores*****
        Dim sbScript As New System.Text.StringBuilder
        sbScript.Append("<script language=javascript>" & vbCrLf)
        sbScript.Append("var arrProvincias = new Array(" & _
                        "'&Aacute;lava','Albacete','Alicante','Almer&iacute;a'," & _
                        "'&Aacute;vila','Badajoz','Baleares','Barcelona'," & _
                        "'Burgos','C&aacute;ceres','C&aacute;diz','Castell&oacute;n'," & _
                        "'Ciudad Real','C&oacute;rdoba','Coru&ntilde;a','Cuenca'," & _
                        "'Gerona','Granada','Guadalajara','Guip&uacute;zcoa'," & _
                        "'Huelva','Huesca','Ja&eacute;n','Le&oacute;n'," & _
                        "'L&eacute;rida','La Rioja','Lugo','Madrid'," & _
                        "'M&aacute;laga','Murcia','Navarra','Orense'," & _
                        "'Asturias','Palencia','Las Palmas','Pontevedra'," & _
                        "'Salamanca','Santa Cruz de Tenerife','Cantabria','Segovia'," & _
                        "'Sevilla','Soria','Tarragona','Teruel'," & _
                        "'Toledo','Valencia','Valladolid','Vizcaya'," & _
                        "'Zamora','Zaragoza','Ceuta','Melilla');" & vbCrLf)
        sbScript.Append("var arrCodigos = new Array('01','02','03','04','05','06','07','08','09','10'," & _
                                                    "'11','12','13','14','15','16','17','18','19','20'," & _
                                                    "'21','22','23','24','25','26','27','28','29','30'," & _
                                                    "'31','32','33','34','35','36','37','38','39','40'," & _
                                                    "'41','42','43','44','45','46','47','48','49','50'," & _
                                                    "'51','52');" & vbCrLf)
        sbScript.Append("function provinciaCP(txt,lbl) {" & vbCrLf)
        sbScript.Append("var cp = String(txt).substring(0,2);" & vbCrLf)
        sbScript.Append("var ind, pos;" & vbCrLf)
        sbScript.Append("for(ind=0; ind<arrCodigos.length; ind++)" & vbCrLf)
        sbScript.Append("{" & vbCrLf)
        sbScript.Append("if (arrCodigos[ind] == cp)" & vbCrLf)
        sbScript.Append("break;" & vbCrLf)
        sbScript.Append("}" & vbCrLf)
        sbScript.Append("pos = (ind < arrCodigos.length)? ind : -1;" & vbCrLf)
        sbScript.Append("if(arrProvincias[pos] != undefined)" & vbCrLf)
        sbScript.Append("{document.getElementById(lbl).innerHTML = arrProvincias[pos];}" & vbCrLf)
        sbScript.Append("else {document.getElementById(lbl).innerHTML = 'Provincia no identificada';}" & vbCrLf)
        sbScript.Append("}" & vbCrLf)
        sbScript.Append("</script>" & vbCrLf)
        Me.Controls.Add(New LiteralControl(sbScript.ToString))
        '************************

        Me.Controls.Add(txt)
        Me.Controls.Add(New LiteralControl("&nbsp;"))
        Me.Controls.Add(lbl)
        txt.Attributes.Add("onChange", "provinciaCP(this.value,'" & lbl.ClientID & "');")
        Me.Controls.Add(New LiteralControl("<script>provinciaCP('" & txt.Text & "','" & lbl.ClientID & "');</script>"))
    End Sub

End Class