在Shiny中隐藏/显示菜单项

library(shiny)

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      sidebarMenu(
        menuItem("菜单项1", tabName = "menu1"),
        menuItem("菜单项2", tabName = "menu2"),
        menuSubItem("菜单项3", tabName = "menu3",
                    conditionalPanel(
                      condition = "input.condition == true",
                      p("这是菜单项3的内容")
                    )
        )
      )
    ),
    mainPanel(
      tabItems(
        tabItem(tabName = "menu1",
                h2("菜单项1的内容")
        ),
        tabItem(tabName = "menu2",
                h2("菜单项2的内容")
        ),
        tabItem(tabName = "menu3",
                h2("菜单项3的内容")
        )
      )
    )
  )
)

server <- function(input, output) {
  # 根据条件设置input$condition的值
  # 这里可以根据需要设置条件，比如根据用户的选择来决定是否显示菜单项3
  observe({
    if (input.menu1 == "menu1") {
      updateTextInput(session, "condition", value = "true")
    } else {
      updateTextInput(session, "condition", value = "false")
    }
  })
}

shinyApp(ui, server)