js实现屏蔽页面鼠标右键

<SCRIPT type="text/javascript">
document.oncontextmenu = function () {
return false;
}
document.onkeydown = function () {
if (event.ctrlKey && event.keyCode == 67) {
return false;
}
}
document.body.oncopy = function () {
return false;
}
</SCRIPT>