Refresh parent window from Child window on close JavaScript

Parent Page

    <form id="form1" runat="server">
    <div>
        Last refreshed:
        <%=DateTime.Now %>
    </div>
    <input type="button" value="Show Popup" onclick="ShowPopup('Child.aspx')" />
    <script type="text/javascript">
        var popup;
        function ShowPopup(url) {
            popup = window.open(url, "Popup", "toolbar=no,scrollbars=no,location=no,statusbar=no,menubar=no,resizable=0,width=100,height=100,left = 490,top = 262");
            popup.focus();
        }
    </script>
    </form>

Child Page

    <form id="form1" runat="server">
    <input type="button" value="Refresh Parent" onclick="RefreshParent()" />
    <script type="text/javascript">
        function RefreshParent() {
            if (window.opener != null && !window.opener.closed) {
                window.opener.location.reload();
            }
        }
        window.onbeforeunload = RefreshParent;
    </script>
    </form>