At this stage, it is supposed that you already know how to code web applications in Shiny with certain complexity. In this chapter, three main topics will be covered that will help you to expand the possibilities of your applications a step further. They are mainly four functions that operate on the server side (that is, they are used in the server.R script):
validate(): This validates the inputs passed according to some conditionisolate(): This prevents the update of a piece of code given a change in a reactive valueobserve(): This provides a reactive context but generates no displayable outputreactiveValues(): This creates a list object whose element can deal with reactive valuesInput updates: These are a group of functions that change one or more characteristics of a specific input (for example,
sliderInputwould requireupdateSliderInput).