使用Prototype.js1.51写 兼容firefox和IE的屏蔽右键和F5等的功能

屏蔽右键：  document.oncontextmenu=function(){return false};

屏蔽F5等功能：

 <script language="javascript" type="text/javascript" >
        Event.observe(document, 'keypress', function(event)
       {        //如果是IE浏览器
                if (Prototype.Browser.IE || document.all)
                {
                     if(event.keyCode==116||event.keyCode==9)
                     {
                        event.keyCode = 0;
                        event.returnValue = false;
                     }//如果是FIRFOX浏览器
                }else
                {
                    if(event.keyCode==116||event.keyCode==9)
                    {
                        Event.stop(event);
                    }
         }                
        });
     </script>