禁止文本框复制和粘贴只能手动输入

<script>
       //禁止粘贴文本框
        function fncKeyStop(evt)
        {
            if(!window.event)
            {
                var keycode = evt.keyCode;
                var key = String.fromCharCode(keycode).toLowerCase();
                if(evt.ctrlKey && key == "v")
                {
                  evt.preventDefault();
                  evt.stopPropagation();
                }
                if(evt.ctrlKey && key == "x")
                {
                  evt.preventDefault();
                  evt.stopPropagation();
                }
            }
        }
</script>