Popup needs to refer back to textbox within a content control

Question

I have a link that is located inside a content control. This link calls a javascript function that opens a popup window containing a calendar and passes it the transformed id from the server of a textbox control using clientid. I need to be able to click on a date and have the popup close and insert the date into the textbox of the id I passed into the function which again, is located inside the content control.

This is the link in the content control:

<a title="Pick Date from Calendar" onclick="calendarPicker('form1.<%= txtstart.ClientId %>');" href="javascript:void(0);">

This is the javascript inside the masterpage:

<script type="text/javascript">
function calendarPicker(strField) {
    var strField = window.open('DatePicker.aspx?field=' + strField, 'calendarPopup', 'width=250,height=190,resizable=yes');
}

The calendar is a calendar control inside its own page and this is the codebehind:

Private Sub Calendar1_DayRender(ByVal sender As Object, ByVal e As DayRenderEventArgs) Handles Calendar1.DayRender
        Dim link As New System.Web.UI.HtmlControls.HtmlGenericControl
Dim strLink As String
e.Cell.Controls.Clear()
link.TagName = "a"
link.InnerText = e.Day.DayNumberText
strLink = "JavaScript:window.opener.document." & Request.QueryString("Field") & ".value = '" & e.Day.Date & "'; window.close();"
link.Attributes.Add("href", strLink)
If (e.Day.IsSelected) Then
  link.Attributes.Add("style", Calendar1.SelectedDayStyle.ToString())
End If
e.Cell.Controls.Add(link)
End Sub

I should also mention the error I'm getting is:

window.opener.document.form1 is undefined

Answer 1

don't use document.form1. use document.getElementById(strField). you'll also have to fix your call to calendarPicker. calendarPicker('<%= txtstart.ClientId %>');

don't put javascript in the href property. use link.Attributes.Add("onclick", strLink)