js 禁止F5刷新代码

<script language="JavaScript">     window.onload = function() { //禁止F5刷新 document.onkeydown = function (e) {  if (e.keyCode === 116) {    return false;  } }; //靜止右鍵 document.oncontextmenu = function() {event.returnValue = false;}     } </script>