Need to pass a dynamically created control to a javascript function

How can I pass a dynamically created control to a javascript function and get the id of the object that was changed?  The code below shows 'undefined'
Dim theCb As New CheckBox() theCb.Text = "Check All" theCb.TextAlign = TextAlign.Right theCb.Attributes.Add("onchange", "CheckBox_Change(this)") theRCell.Controls.Add(theCb) function CheckBox_Change(sender) { alert($(sender).attr('id')); }