Javascript禁止页面刷新、后退

<script language="javascript">
//禁止用F5键

function document.onkeydown()
{
          if ( event.keyCode==116)
          {
                  event.keyCode = 0;
                  event.cancelBubble = true;
                  return false;
          }
}
        
//禁止右键弹出菜单

function document.oncontextmenu()
{
      return false;
}
        
//下面代码实现全屏显示

function window.onload(){
      var Request = new Array();//保存参数

      var s = location.search.substring(1);
      if (s && s!=""){
      var list = s.split("&");
for (var i=0; i < list.length; i++){
var pair = list[i].split("=");
if (pair[0] && pair[0] !=""){
Request[unescape(pair[0])] = unescape(pair[1]);
}
}
      }
        
      var fullscreen=Request["fullscreen"];
      if(fullscreen!="yes"){
      var file =self.location;
      var a = window.open("about:blank","","fullscreen=yes")
      self.opener=null
      self.close()
      a.location=file + "?fullscreen=yes";
      }
}
</script>


<script language="Javascript"><!--
//屏蔽鼠标右键、Ctrl+N、Shift+F10、F11、F5刷新、退格键

//Author: meizz(梅花雨) 2002-6-18

function document.oncontextmenu(){event.returnValue=false;}//屏蔽鼠标右键

function window.onhelp(){return false} //屏蔽F1帮助

function document.onkeydown()
{
if ((window.event.altKey)&&
((window.event.keyCode==37)|| //屏蔽 Alt+ 方向键 ←

(window.event.keyCode==39))) //屏蔽 Alt+ 方向键 →

{
alert("不准你使用ALT+方向键前进或后退网页！");
event.returnValue=false;
}
/* 注：这还不是真正地屏蔽 Alt+ 方向键，
因为 Alt+ 方向键弹出警告框时，按住 Alt 键不放，
用鼠标点掉警告框，这种屏蔽方法就失效了。以后若
有哪位高手有真正屏蔽 Alt 键的方法，请告知。*/
if ((event.keyCode==8) || //屏蔽退格删除键

(event.keyCode==116)|| //屏蔽 F5 刷新键

(event.ctrlKey && event.keyCode==82)){ //Ctrl + R

event.keyCode=0;
event.returnValue=false;
}
if (event.keyCode==122){event.keyCode=0;event.returnValue=false;} //屏蔽F11

if (event.ctrlKey && event.keyCode==78) event.returnValue=false; //屏蔽 Ctrl+n

if (event.shiftKey && event.keyCode==121)event.returnValue=false; //屏蔽 shift+F10

if (window.event.srcElement.tagName == "A" && window.event.shiftKey)
window.event.returnValue = false; //屏蔽 shift 加鼠标左键新开一网页

if ((window.event.altKey)&&(window.event.keyCode==115)) //屏蔽Alt+F4

{
window.showModelessDialog("about:blank","","dialogWidth:1px;dialogheight:1px");
return false;
}
}
</script>