键盘禁止

    document.onkeydown = function test(){    

                    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;    
                      }    
                }