使用updateNavbarPage为>2页添加“上一页”按钮(也适用于updateTabsetPanel)

library(shiny)

ui <- navbarPage(
  title = "My Shiny App",
  id = "navbar",
  tabPanel("Page 1",
           actionButton("nextBtn1", "Next")
  ),
  tabPanel("Page 2",
           actionButton("nextBtn2", "Next")
  ),
  tabPanel("Page 3",
           actionButton("nextBtn3", "Next")
  )
)

server <- function(input, output, session) {
  observeEvent(input$nextBtn1, {
    updateNavbarPage(session, "navbar", selected = "Page 2",
                     tags$li(class = "previous",
                             actionLink("prevBtn", "上一页")
                     )
    )
  })
  
  observeEvent(input$nextBtn2, {
    updateNavbarPage(session, "navbar", selected = "Page 3",
                     tags$li(class = "previous",
                             actionLink("prevBtn", "上一页")
                     )
    )
  })
  
  observeEvent(input$prevBtn, {
    updateNavbarPage(session, "navbar", selected = "Page 1")
  })
}

shinyApp(ui, server)