jQuery désactive le retour du clavier, bloque l'actualisation F5 et désactive le clic droit_jquery

$(document).ready(function(){ 
 $(document).bind("keydown",function(e){ 
  var e=window.event||e; 
  if(e.keyCode==116){ 
   e.keyCode = 0; 
   return false; 
  } 
 }) 
})

$(document).keydown(function(event){
   
     //屏蔽 Alt+ 方向键 ← 
     //屏蔽 Alt+ 方向键 →
     if ((event.altKey)&&((event.keyCode==37)||(event.keyCode==39)))  
     { 
        event.returnValue=false; 
        return false;
     }
 
     //屏蔽退格删除键 
     if(event.keyCode==8){
        return false; 
     }
        
     //屏蔽F5刷新键 
     if(event.keyCode==116){
        return false; 
     }
 
    //屏蔽alt+R 
    if((event.ctrlKey) && (event.keyCode==82)){
       return false; 
    }

 });

$(document).ready(function() { 
$(document).bind("contextmenu",function(e) { 
alert("sorry! No right-clicking!"); 
return false; 
}); 
}); 

$(document).keydown(function (e) { 
var doPrevent; 
if (e.keyCode == 8) { 
var d = e.srcElement || e.target; 
if (d.tagName.toUpperCase() == 'INPUT' || d.tagName.toUpperCase() == 'TEXTAREA') { 
doPrevent = d.readOnly || d.disabled; 
} 
else 
doPrevent = true; 
} 
else 
doPrevent = false; 

if (doPrevent) 
e.preventDefault(); 
});