How to make a DataTable actually become hidden in a Shiny app

hide-datatable-shiny.R

# -------------------------------------------------------------------
# ------------------ HIDIND A DATATABLE IN SHINY --------------------
# -------------------------------------------------------------------


# -------------------------------------------------------------------
# --- EXAMPLE 1: this sets the datatable's underlying dataframe to --
# --- NULL, inside a reactive (recalculated whenever a checkbox is --
# --- clicked). While this does result in the datatable disappearing
# --- from view, the height does not show ---------------------------
# -------------------------------------------------------------------
# -------------------- does not work as intended --------------------
library(shiny)
library(shinydashboard)
library(DT)

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(checkboxInput("chk", label = "NULL: ", value = T)),
  dashboardBody(
    box(width = 8, DT::dataTableOutput("test"))
  )
)

server <- function(input, output, session) {
  df <- reactive({
    if (input$chk) NULL else data.frame(A = 1:20, B = 2*1:20)
  })
  
  output$test <- DT::renderDataTable({
    datatable(df())
  })
}

shinyApp(ui = ui, server = server)



# -------------------------------------------------------------------
# --- EXAMPLE 2: this leaves the datatable's underlying dataframe ---
# --- untouched, and instead uses shinyjs to hide the dataTableOutput
# --- when the checkbox is clicked. Now, the height readjusts as ----
# --- expected ------------------------------------------------------
# ------------------------ works as intended ------------------------
library(shiny)
library(shinydashboard)
library(DT)
library(shinyjs) # requires shinyjs !

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(checkboxInput("chk", label = "NULL: ", value = T)),
  dashboardBody(useShinyjs(),
    box(width = 8, DT::dataTableOutput("test"))
  )
)

server <- function(input, output, session) {
  observeEvent(input$chk, {
    if (input$chk) hide("test") else show("test")
  })
  
  output$test <- DT::renderDataTable({
    datatable(data.frame(A = 1:20, B = 2*1:20))
  })
}

shinyApp(ui = ui, server = server)