I found a similar case here, not no concrete answer: shiny: passing reactiveValues to conditionalPanel
but it gave me the idea that I need to set variable with session$sendCustomMessage
in server.R and then extract it with Shiny.addCustomMessageHandler
in ui.R. However, I can't figure out how to use the variable in the conditional panel.
Here is my contrived example (I know I can easily condition on input.select1, to get it working):
https://gist.github.com/anonymous/6013ffb888ef22b5aa110ddcafc5659a
Thanks