JS代码屏蔽鼠标右键Ctrl+N、Shift+F10、F11、F5刷新、退格键等按键

代码：

<script>
//屏蔽鼠标右键Ctrl+N、Shift+F10、F11、F5刷新、退格键
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; } 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>