如何在Shiny应用中实现按钮显示？附现有代码片段

First, you need to initialize shinyjs in your UI (this step was missing in your original code) using useShinyjs(). Then, in the server, we’ll set up a reactive observer to listen for clicks on the "Fetch tweets" button and reveal your hidden divs using shinyjs::show().

Here’s the full working code:

library(shiny)
library(shinyjs)
library(shinydashboard)

UI <- fluidPage(
  # Initialize shinyjs (required for show/hide functionality)
  useShinyjs(),
  
  actionButton("get_tweets", "Fetch tweets"),
  numericInput("tweet_amount", "Set the amount of Tweets", 10, min = 10, max = 1000),
  selectInput("tweet_name", "Select the tweeter", selected = NULL, choices = c("@RealDonaldTrump")),
  
  # Hidden elements
  hidden(div(id="status_update", verbatimTextOutput("status"))),
  hidden(div(id="tweet_fetcher", verbatimTextOutput("status2")))
)

Server <- function(input, output, session) {
  # Trigger actions when "Fetch tweets" button is clicked
  observeEvent(input$get_tweets, {
    # Show the hidden divs
    shinyjs::show("status_update")
    shinyjs::show("tweet_fetcher")
    
    # Optional: Add sample content to the revealed outputs
    output$status <- renderPrint({
      "Status: Fetching tweets..."
    })
    
    output$status2 <- renderPrint({
      paste("Successfully fetched", input$tweet_amount, "tweets from", input$tweet_name)
    })
  })
}

shinyApp(UI, Server)

Key Details: #

• useShinyjs(): This initializes the shinyjs library in your app—without it, the show/hide functions won’t work.
• observeEvent(input$get_tweets, {...}): This creates a reactive trigger that runs every time the "Fetch tweets" button is pressed.
• shinyjs::show("div_id"): These lines make your hidden divs visible when the button is clicked.
• The renderPrint blocks add sample text to demonstrate the revealed elements are functional. You can replace this with your actual tweet-fetching logic later.

If you want to hide the elements again (e.g., on a reset action), you can use shinyjs::hide("div_id") in another observer or button handler.

内容的提问来源于stack exchange，提问作者Henk Straten