Q: How can I replace or fix old www.dynarch.com calendar I have this ancient calendar in use with my simple project management program. It stopped working, date picker pop-up does not show anymore.
I checked from Chromium console what the problem is. I got this error :
Uncaught TypeError: Cannot read property 'replace' of undefined
at Calendar._displayWeekdays (calendar.js:15)
at Calendar.create (calendar.js:15)
at HTMLImageElement.triggerEl.(/task/anonymous function) (https://www.xxxx.xxx/task/jscalendar/calendar-setup.php?format=%25d%2F%25m%2F%25y:34:2702)
Calendar._displayWeekdays @ calendar.js:15
Calendar.create @ calendar.js:15
triggerEl.(anonymous function) @ calendar-setup.php?format=%d%2F%m%2F%y:34

I have no idea how to fix it or how to replace this old datepicker.
I updated it to newer version, it didn't help. I updated jquery, it didn't help.
I'm totally lost now how to get it working again.
I'm really grateful if someone could help me to fix this problem.
Here is calendar.js file in question : calendar.js
Here is calendar-setup.php : calendar-setup.php
There is also calendar-setup.js, here : calendar-setup.js
