This script can send multiple invites from facebook page at the same time. At first go to the facebook page for which you want to send the invite, then clicl on the invite link situated on the left side of the page. After clicking a pop-up will open with the list of all friends with the invite button. Scroll down to the last friend of the list. Then right click on any of the invite button and select inspect element, then in console paste the script and run it.
The Invite will be sent in a moment just after click.