禁止右键及右键菜单js

<script language="JavaScript">
<!--
if (window.Event)
document.captureEvents(Event.MOUSEUP);
function nocontextmenu()
{
event.cancelBubble = true
event.returnValue = false;
return false;
}
function norightclick(e)
{
if (window.Event)
{
if (e.which == 2 || e.which == 3)
return false;
}
else
if (event.button == 2 || event.button == 3)
{
event.cancelBubble = true
event.returnValue = false;
return false;
}
}
document.oncontextmenu = nocontextmenu; // for IE5+
document.onmousedown = norightclick; // for all others
//-->
</script>