Advanced Shiny functions are definitely harder to understand, as they are conceptually different from everything seen so far in Shiny. However, they expand the application's possibilities enormously. This can be seen even in the example codes. Before this chapter, the examples were much simpler in terms of the application's functionalities since the reactivity process was also much simpler; whenever an input changes, the output is updated. Thanks to these functions, the reactivity process can be much more complex, the execution can be controlled, invisible processes can be triggered, and so on. Dealing with this complexity, far from being a problem, is a huge advantage.

The functions presented in this chapter belong, metaphorically speaking, to a second level of functions in terms of complexity. There are some other more advanced functions that provide more advanced possibilities. However, as this is an introductory book, these will not be covered here. If you are interested in more...