cara tak boleh copy html/javascript

<script language="JavaScript1.1">
<!--
function right(mousebutton)
{
var msg1 = "opsss?! hihi";

if (navigator.appName == 'Netscape' && mousebutton.which==3)
{
alert(msg1);
return false;
}
else

if (navigator.appName == 'Netscape' && mousebutton.which==1)
{
alert(msg2);
return false;
}
else

if (navigator.appName == 'Microsoft Internet Explorer' && event.button == 2)
{
alert(msg1);
return false;
}
else

if (navigator.appName == 'Microsoft Internet Explorer' && event.button == 2)
{
alert(msg2);
return false;
}
return true;
}
document.onmousedown = right;
// -->
</script>