As we all have many friends in our accounts and it takes too much time to select them all one by one, just a wastage of time.
1. Login to your facebook account.
2. Navigate to the page or event where to select your all friends.
3. Click on Invite friends.
4. New box will appear, scroll down the list until your all friends name is loaded.
5. It will look like,
6. Now put this script in the address bar, and press Enter.