I would like to build something that equals the functionality of the shiny functions navbarPage() and navbarMenu(). However when I create two different tabs (NAVONE and NAVTWO in my app below) I am able to render output within the first tab (which is not hidden by default), but not able to render output within the second tab. Its not clear to me what differs between both content sections.

library(shiny)
if (interactive()) {
  options(device.ask.default = FALSE)
  
  ui = fluidPage(
    
    ###NAVBAR
    tags$div(class = 'nav',
             tags$button('NAVONE', class = 'navlinks', id = "defaultOpenNav", onclick = 'openNav(event, "NAVONE")'),
             tags$button('NAVTWO', class = 'navlinks', onclick = 'openNav(event, "NAVTWO")')),
    
    ###NAVCONTENT
    tags$div(class = 'navcontent', id = 'NAVONE',
             actionLink(inputId = "actnOne", "click to create plot for nav one"),
             plotOutput(outputId = "plotOne")),
    
    tags$div(class = 'navcontent', id = 'NAVTWO',
             actionLink(inputId = "actnTwo", "click to create plot for nav two"),
             plotOutput(outputId = "plotTwo")),
    
    ###JAVASCRIPT
    tags$script(HTML(
      
      "function openNav(evt, NavToOpen) {
        // Declare all variables
        var i, navcontent, navlinks;

        // Get all elements with class = 'navcontent' and hide them
        navcontent = document.getElementsByClassName('navcontent');
        for (i = 0; i < navcontent.length; i++) {
        navcontent[i].style.display = 'none';
        }

        // Get all elements with class = 'tablinks' and remove the class 'active'
        document.getElementById(NavToOpen).style.display = 'block';
        evt.currentTarget.className += ' active';
        }

        // navcontent to be open by default
        document.getElementById('defaultOpenNav').click();"
    ))
  )
  
  server = function(input, output, session){
    
    ###PLOT FOR NAV ONE
    observeEvent(input$actnOne, {
      output$plotOne = renderPlot({
        hist(iris$Sepal.Length)
      })
    })
    
    ###PLOT FOR NAV TWO
    observeEvent(input$actnTwo, {
      output$plotTwo = renderPlot({
        hist(iris$Sepal.Length)
      })
    })
  }
  shinyApp(ui, server)
}