FindContol Solution to add Javascript to a control from a user control

Here is a great solution to finding a control using FindControl method from a user control. TargetcontrolID is the public property for TextBoxFooExtender (User Control). _txt is the targeted TextBox assuming it is found.

    protected override void CreateChildControls()
    {
        txt = (TextBox)this.Parent.FindControl(TargetControlID);
        if (txt != null) {
            _txt.Attributes.Add("ondblclick", "alert('foo')");
        }
        base.CreateChildControls();
    }