[jQuery] 백스페이스, 뒤로가기 방지하기

$(document).bind("keydown",function(e){
    if( (event.ctrlKey == true && (event.keyCode == 78 || event.keyCode == 82)) 
        || (event.keyCode == 116) || (e.keyCode==8) ) {
        event.keyCode = 0;
        event.cancelBubble = true;
        event.returnValue =false;
    }
});