How To Block F5(Refresh) Key In IE and Firefox

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
    <title>Block F5 Key In IE & Mozilla</title>

    <script language="JavaScript">

        var version = navigator.appVersion;

        function showKeyCode(e) {
            var keycode = (window.event) ? event.keyCode : e.keyCode;

            if ((version.indexOf('MSIE') != -1)) {
                if (keycode == 116) {
                    event.keyCode = 0;
                    event.returnValue = false;
                    return false;
                }
            }
            else {
                if (keycode == 116) {
                    return false;
                }
            }
        }

    </script>

</head>
<body onload="JavaScript:document.body.focus();" onkeydown="return showKeyCode(event)">
</body>
</html>