invite facebook friend from your application or website,use this small lines of code and send invitation to all facebook friends to visit your website.i also used this script its working nicely.
your domain must be ssl certified because facebook didn't allowing unsecured domains.
<script src="http://connect.facebook.net/en_US/all.js"></script>
<script>
FB.init({
appId:'APP_ID',
cookie:true,
status:true,
xfbml:true
});
function FacebookInviteFriends()
{
FB.ui({
method: 'apprequests',
message: 'Your Message diaolog'
});
}
</script>
//HTML Code
<div id="fb-root"></div>
<a href='#' onclick="FacebookInviteFriends();">
Facebook Invite Friends Link
</a>
add this below code to your website main page..
<script type='text/javascript'>
if (top.location!= self.location)
{
top.location = self.location
}
</script>
for more detail you can check:- http://www.9lessons.info/2012/07/facebook-invite-friends-api.html