Additionally

DOM templates

One of the advantages of this calendar is that you can easily customize its HTML markup with the DOMTemplates parameter.

Thanks to this, you can safely add your button or any other html element to your calendar.

DOMTemplates takes the type of a calendar as a key. And types take a string as a value.

In the example below, we'll customize the title of our calendar, but only for type: 'default' and add a regular button.