Custom dependencies
The last dependency contains custom JS and CSS code necessary for Shiny to work, that is:
Fine-tune the layout.
Register input/output and handle every single input/output action.
Detailed mechanisms are studied in Chapters 12 and 13.
Initialize and control the R/JS communication, as shown in Chapter 11.3.1.
Handle alerts/modals/notifications.
Chapters 10.6.3, 12, 15 and 19 showcase the most important elements of those custom files.