防止刷新和后退的js

<script language="JavaScript">

function onKeyDown()
{
      if ( (event.altKey) || ((event.keyCode == 8) &&
            (event.srcElement.type != "text" &&
            event.srcElement.type != "textarea" &&
            event.srcElement.type != "password")) ||
            ((event.ctrlKey) && ((event.keyCode == 78) || (event.keyCode == 82)) ) ||
            (event.keyCode == 116) ) 
      {
               event.keyCode = 0;
               event.returnValue = false;
      }
}
document.onkeydown = onKeyDown;

function stop(){   
      return false;
}
document.oncontextmenu=stop;
</script>