网页不让复制粘贴

<script type="text/javascript">
function stop() {
return false;
}
document.oncontextmenu = stop;
document.onselectstart = stop;
document.oncopy = stop;
document.oncut = stop;
document.onpaste = stop;
</script>

$('#txt_input').bind("cut copy paste", function(e) {  
                            alert('Copy Paste is disabled');  
                            e.preventDefault();  
                        });