Facebook Events Web Calendar Sync Reminder

WHAT IT DOES

This tool automatically extracts event information from Facebook event pages, including the event name, date, time, and location. It displays a compact panel showing these details alongside a countdown timer to the event start. With a single click, you can open Google Calendar or Apple Calendar with all event details pre-filled, eliminating the need to manually copy and paste information. The panel also provides a "Copy ICS" button that generates standard calendar data for manual import into any calendar application.

WHERE IT RUNS

The script activates on any Facebook event page (facebook.com/events/*). It reads the page structure to locate event information, displaying a draggable overlay panel that stays visible as you browse. The panel works on both public and private events, reading only the information displayed on the page you are viewing.

HOW TO USE

Navigate to any Facebook event page. The panel will appear showing the event name, date, time, and location if detected. Choose your preferred calendar service (Google or Apple) using the toggle buttons in the panel. Click "Add to Calendar" to open your selected calendar service with the event details pre-populated. The first time you do this for an event, the script marks it as synced to avoid duplicate reminders. Use "Copy ICS" to generate an ICS file content and copy it to your clipboard for manual import into Outlook, Thunderbird, or other calendar applications. The "Remind me" setting controls how many days before the event the countdown turns orange as a visual reminder.

THE TECHNICAL MECHANISM

The script employs a cascading extraction strategy: it first tries modern Facebook data-testid attributes, then falls back to class-based selectors, and finally uses a TreeWalker to scan visible text nodes for date and location patterns. This multi-layered approach ensures the script works even as Facebook's markup evolves. For time detection, it parses common time formats (including 12-hour and 24-hour) and automatically sets a default 2-hour duration for calendar entries. The calendar URL generation uses the standard Google Calendar template format, while the ICS export builds a complete VCALENDAR block compliant with RFC 5545. All synced event data is stored locally using GM_setValue with per-event keys derived from the Facebook event ID in the URL.

THE PANEL

The panel is fully draggable by its header and remembers its position on the page across sessions. It can be collapsed to a small bubble using the minimize button, then restored by clicking the bubble. The panel resizes automatically to fit its content and can be closed with the Escape key or by clicking the close button. The panel's position and state persist globally, so it returns to the same location on subsequent visits to any Facebook event page.

PLEASE NOTE

Requires the free BotGentz extension to run. Facebook frequently updates its page structure, which may temporarily affect the script's ability to extract certain details — updates will be released as needed. All event data is stored locally in your browser and is never transmitted externally. The script only reads visible page content and does not modify your Facebook account, send messages, or perform any actions on your behalf.