Why when I do this:

<body>
    <script>
        Object.prototype.extends = function (from, impl) {
            //do something
        }

    </script>
    <form id="form1" runat="server">
        <ext:ResourceManager runat="server"></ext:ResourceManager>
        <ext:Window runat="server" Title="Test"></ext:Window>
    </form>
</body>
Hides all Ext.Net components.

I´m trying to create my own "extends" method for my javascript framework