Demo on submit button with pop-up (IN PROGRESS)

server.R

# server.R

library("shiny")

shinyServer(
  function(session, input, output) {
      
      observe({
          if (is.null(input$submit) || input$submit == 0){return()}
          js_string <- 'alert("Do you want to submit now?");'
          session$sendCustomMessage(type='jsCode', list(value = js_string))
          text <- isolate(input$inText)
          output$outText <- renderUI({
              h4(text)
          })
      })
      
  }
)

ui.R

# ui.R

library("shiny")

shinyUI(
  basicPage(
    tags$head(
      tags$style(type='text/css', 
        "select, textarea, input[type='text'] {margin-bottom: 0px;}"
        , "#submit {
          color: rgb(255, 255, 255);
          text-shadow: 0px -1px 0px rgba(0, 0, 0, 0.25);
          background-color: rgb(189,54,47);
          background-image: -moz-linear-gradient(center top , rgb(238,95,91), rgb(189,54,47));
          background-repeat: repeat-x;
          border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
        }"
      ),
      tags$script(HTML('
          Shiny.addCustomMessageHandler("jsCode",
            function(message) {
              eval(message.value);
            }
          );'
      ))
    )
    ,
    textInput(inputId = "inText", label = "", value = "type text here")
    ,
    actionButton(inputId = "submit", label = "Submit")
#  
#   alternative approach: button with pop-up
#    , tags$button("Activate", id = "ButtonID", type = "button", class = "btn action-button", onclick = "return confirm('Are you sure?');" )
    ,
    tags$br()
    ,
    tags$hr()
    ,
    uiOutput("outText")
  )
)