show with app
function(input, output) {

  # You can access the value of the widget with input$action, e.g.
  output$value <- renderPrint({ input$action })

}
fluidPage(
    
  # Copy the line below to make an action button
  actionButton("action", label = "Action"),
  
  hr(),
  fluidRow(column(2, verbatimTextOutput("value")))
  
)