The Calendar ( cal and cal list ) are more complex than the standard PHP templates as it uses the Fullcalender (V3) library which is javascript driven.
Whilst there are filters to add options with values, occasionally it is desirable to be able to alter the javascript that is rendering events.
There are two filters wfea_cal_extra_js and wfea_cal_list_extra_js to help with this.
This is a more complex option and is you need support please do raise a support ticket.
The following is an example that adds the image to the calendar front end – not just the tool tip. It has been implemented as a mini plugin which you can use as-is or modify to your needs.
If you want to use as-is you can get the zip file from here:
