javaScript禁止粘贴复制

<html><head runat="server">
    <title></title>
    <script language="javascript" type="text/javascript">
        function RightClick() {
            if (event.button == 2) {
                alert('禁止右键复制！');
            }
        }

        function CtrlKeyDown() {
            if (event.ctrlKey) {
                alert('不当的拷贝将损害您的系统！');
            }
        }
    </script>
</head>

</body>