The first thing to note is that Shiny programs are the easiest to build and understand using two scripts, which are kept within the same folder. They should be named
ui.R. Throughout this book, all code will have the commented
ui.R headers to indicate which code goes in which file. The code is available at github.com/ChrisBeeley/basicGoogleAnalytics2ndEdition.
ui.R file is a description of the UI and is often the shortest and simplest part of a Shiny application. Note the use of the
# character, which marks lines of code as comments that will not be run, but which are for the benefit of humans producing the following code:
library(shiny) # Line 1 ...