Log in to Facebook and click the "What are you planning?" box from the main screen. Fill out the event details and click the "Create Event" button to create a new event. Or find an event that already exists on Facebook and click the "Yes" or "Maybe" buttons to designate your attendance. Click on the "Select Guests to Invite" button that appears on the left-hand side of the event page, underneath the event's picture.
Scroll the list of friends all the way to the bottom. The list will get longer each time as it refreshes with new friends from your friends list. Keep scrolling the list of friends downward until you reach the end of the list and all your friends are displayed in the "Invite Friends" box.
Copy the following line of code and paste it into the browser's Address Bar:
Press the "Enter" key and wait for the browser to process the code. The page will refresh and all the friends displayed in the "Invite Friends" box should now be selected. Click the "Submit" button to send the invitations to all the selected friends.