I remember having used an option setting that enable to print in the R console the messages between the server and ui while a shiny app is running. This option is really useful to understand what is happening in the app. However I cant remember the name of that option and can not find it anymore in the documentation. Can someone can tell what is that option ? Thanks!
I finally found it :
options(shiny.trace=TRUE)
Before running the app. I find it extremely useful to understand what is appending. I don't know why it is not more documented.
R Studio lists a nice summary of R Shiny global options available here
You may wish to turn both of these on:
options(shiny.trace=TRUE)
options(shiny.fullstacktrace=TRUE)
来源：https://stackoverflow.com/questions/23002712/shiny-what-is-the-option-setting-to-display-in-the-console-the-messages-between