Rated 4 out of 5 stars

I wanted to clarify suwa5's comment. In order to turn on js and make the extension work correctly, you need to go to Preferences->Advanced->Config Editor and set "calendar.icaljs" to true (search for icaljs and double click on it).

Thanks for developing this useful extension!

This review is for a previous version of the add-on (1.0.3).