首次加载应用时，无法根据点击事件显示小部件

Question

I have the shiny dashboard below where the widget of the right sidebar is supposed to be displayed only when the "Plot" tabpanel is active and this actually happens except of the 1st time the app is loaded when the widget is displayed in the 'Summary' tabpanel as well. I understand that this is happening because the activation comes with the click on tabpanel name. But how can I fix it?

library(golem)
library(shiny)
library(shinydashboard)
library(shinydashboardPlus)
shinyApp(
  ui = dashboardPagePlus(
    header = dashboardHeaderPlus(
      enable_rightsidebar = TRUE,
      rightSidebarIcon = "gears"
    ),
    sidebar = dashboardSidebar(),
    body = dashboardBody(
      golem::activate_js(),
      navbarPage("Navbar!",
                 tabPanel("Summary"

                 ),
                 tabPanel("Plot"
                 )), 
      tags$script(
        '$("a[data-toggle=\'tab\']").click(function(){
          Shiny.setInputValue("tabactive", $(this).data("value"))
        })'
      )
    ),
    rightsidebar = rightSidebar(
      background = "dark",
      rightSidebarTabContent(
        id = 1,
        title = "Tab 1",
        icon = "desktop",
        active = TRUE,
        uiOutput("sl")

      )

    ),
    title = "Right Sidebar"
  ),
  server = function(input, output) {
    output$sl<-renderUI({
      sliderInput(
        "obs",
        "Number of observations:",
        min = 0, max = 1000, value = 500
      )
    })

    observeEvent( input$tabactive , {
      if (input$tabactive == "Plot"){
        golem::invoke_js("showid", "sl")
      } else {
        golem::invoke_js("hideid", "sl")
      }
    })



  }
)

Answer 1

You can suppress the initial rendering via adding req(input$tabactive) to your renderUI call:

library(golem)
library(shiny)
library(shinydashboard)
library(shinydashboardPlus)

shinyApp(
  ui = dashboardPagePlus(
    header = dashboardHeaderPlus(
      enable_rightsidebar = TRUE,
      rightSidebarIcon = "gears"
    ),
    sidebar = dashboardSidebar(),
    body = dashboardBody(
      golem::activate_js(),
      navbarPage("Navbar!",
                 tabPanel("Summary"

                 ),
                 tabPanel("Plot"
                 )), 
      tags$script(
        '$("a[data-toggle=\'tab\']").click(function(){
          Shiny.setInputValue("tabactive", $(this).data("value"))
        })'
      )
    ),
    rightsidebar = rightSidebar(
      background = "dark",
      rightSidebarTabContent(
        id = 1,
        title = "Tab 1",
        icon = "desktop",
        active = TRUE,
        uiOutput("sl")

      )

    ),
    title = "Right Sidebar"
  ),
  server = function(input, output) {
    output$sl <- renderUI({
      req(input$tabactive)
      sliderInput(
        "obs",
        "Number of observations:",
        min = 0, max = 1000, value = 500
      )
    })

    observeEvent( input$tabactive , {
      if (input$tabactive == "Plot"){
        golem::invoke_js("showid", "sl")
      } else {
        golem::invoke_js("hideid", "sl")
      }
    })
  }
)