FullCalendar Event Hover with title, body, event date and URL

I'm looking for this functionality as well. It is in the Fullcalendar JS library, but is it in this module?

I don't think this module have this feature. Even if we try to add if try to implement through custom approach. Looks like html tags are getting stripped off in the view.

I think hovering feature is a must have feature show show title and description When we hover onto a title. Suppose if title is two long (Suppose 7-10 words ) then it will only show few 3-4 words only on calendar. There is no way to read the complete title.

So Now I am able to get this functionality working and below is the code snippet I had to write to get this working

function custom_calendar_preprocess_views_view__fullcalendar(array &$variables): void {
  if (isset($variables['rows']['#attached']['drupalSettings']['fullcalendar']['js-view-dom-id-' . $variables['dom_id']]['options']['eventSources'])) {
    $events = $variables['rows']['#attached']['drupalSettings']['fullcalendar']['js-view-dom-id-' . $variables['dom_id']]['options']['eventSources'][0];
    // Update the events to include descriptions from nodes.
    $events = array_map(function ($event) {
      // Load the node by ID and set the description from body field.
      $node = \Drupal::entityTypeManager()->getStorage('node')->load($event['id']);
      if ($node instanceof NodeInterface && $node->hasField('body') && !$node->get('body')->isEmpty()) {
        $description = $node->body->value;
        // Trim the description to 160 chars.
        $event['description'] = mb_substr(strip_tags($description), 0, 160);
      }
      else {
        $event['description'] = '';
      }
      return $event;
    }, $events);
    // Update the events in the drupalSettings.
    $variables['rows']['#attached']['drupalSettings']['fullcalendar']['js-view-dom-id-' . $variables['dom_id']]['options']['eventSources'][0] = $events;
  }
}

and below is the js file content

(function eventTooltip(Drupal, drupalSettings, once, tippy, FullCalendar) {
  Drupal.behaviors.calendarTooltip = {
    attach(context) {
      // Resets the "once" behavior for .fullcalendar--wrapper
      once.remove('fullCalendarBuild', '.fullcalendar--wrapper', context);
      once('fullCalendarBuild', '.fullcalendar--wrapper', context).forEach(
        (calendarEl) => {
          const domId = calendarEl.id;
          if (drupalSettings.fullcalendar.hasOwnProperty(domId)) {
            const settings = drupalSettings.fullcalendar[domId];
            const calendarOptions = settings.options;
              calendarOptions.eventDidMount = function addTooltip(info) {
                // Format the date as "MMM d" (e.g., "Jan 1")
                const formattedDate = info.event.start.toLocaleDateString(undefined, { month: 'long', day: 'numeric' });
                // Custom tooltip logic
                tippy(info.el, {
                  content: `<div class="event-tooltip-title">${info.event.title}</div><div class="event-tooltip-date">${formattedDate}</div><div class="event-tooltip-description">${info.event.extendedProps.description}</div>`,
                  allowHTML: true,
                });
              };
            // Render the calendar as usual
            const calendar = new FullCalendar.Calendar(calendarEl, calendarOptions);
            calendar.render();
          }
        }
      );
    }
  };
})(Drupal, drupalSettings, once, window.tippy, window.FullCalendar);

I am not able to find any way to reuse the existing calendar object and add the callback function before rendering.

Is the code in here helpful? https://www.drupal.org/project/fullcalendar/issues/3527506 ✨ Extensible javascript FullCalendar object. Active

yes that option I already tried. but I could not see anything to check if calendar is already rendered or not

Providing some form of tooltip display option is definitely a priority for this module. There seem to be quite a few examples online (including on FullCalendar.io) that show using Tippy.js, but it doesn't look like that library's repo has seen any updates in over 3 years and has now been marked as read only, which doesn't give me confidence. Floating UI looks to be actively maintained which makes it look like a better candidate.

As to how this could be configured for Drupal, I would favour allowing a site builder to choose a view mode that would be used to render the content that would appear within the tooltip. That should allow virtually limitless customization options (including the use of custom templates, if desired) but does have the potential drawback that a misconfiguration (for example, choosing view mode that hasn't been set up for a content type) could cause full nodes to be rendered for the tooltip displays, causing the view render to be huge.

Yes this could be the good option