Disable Refresh Button and F5 in WebSites

document.attachEvent("onkeydown", my_onkeydown_handler);
        function my_onkeydown_handler() {
            switch (event.keyCode) {
                case 116: // 'F5'
                    event.returnValue = false;
                    event.keyCode = 0;
                    window.status = "We have disabled F5";
                        break;
            }
        }