SOLVED! How to Invite All Facebook Friends To An Event?

Here is the magic snippet of code that makes this possible:

javascript:elms=document.getElementById(‘friends’).getElementsByTagName(‘li’);for(var fid in elms){if(typeof elms[fid] === ‘object’){fs.click(elms[fid]);}}

http://funkyplumbo.com/2009/04/21/how-to-invite-all-your-friends-on-facebook-to-your-event-in-one-go/

Go to your event/group/page, click invite people and then paste this snippet in the URL field of your browser.
Left-click the mouse in the URL field and hit Enter. Your invitations will not be sent yet, but all your friends will be selected. Click the “Invite” or “Send” button on the Facebook page to finally send the invites.