Disabling Right click

<script type="text/javascript">
function disableRightClick(btnClick) {
    if (navigator.appName == "Netscape" && btnClick.which == 3) { // check for netscape and right click
        alert("Right Click is disabled");
        return false;
    }
    else if (navigator.appName =="Microsoft Internet Explorer" && event.button == 2) { // for IE and Right Click
        alert("Right Click is disabled");
        return false;
    }
}
document.onmousedown = disableRightClick;
</script>

function DisableRightClick(event)
{
//For mouse right click
if (event.button==2)
{
alert("Right Clicking not allowed!");
}
}