Shiny: Barras de progresso por tempo indeterminado

Outra possibilidade é simplesmente tornar as listras mais visíveis e definir o valor de progresso para 1:

server <- function(input, output) {
  output$plot <- renderPlot({
    input$goPlot # Re-run when button is clicked

    dat <- data.frame(x = rnorm(10), y = rnorm(10))

    withProgress(message = 'Making plot', value = 1, {
      Sys.sleep(20)
    })

    plot(dat$x, dat$y)
  })
}

ui <- shinyUI(basicPage(
  tags$head(tags$style(HTML("
    .progress-striped .bar {
      background-color: #149bdf;
      background-image: -webkit-gradient(linear, 0 100%, 100% 0, color-stop(0.25, rgba(255, 255, 255, 0.6)), color-stop(0.25, transparent), color-stop(0.5, transparent), color-stop(0.5, rgba(255, 255, 255, 0.6)), color-stop(0.75, rgba(255, 255, 255, 0.6)), color-stop(0.75, transparent), to(transparent));
      background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, 0.6) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, 0.6) 50%, rgba(255, 255, 255, 0.6) 75%, transparent 75%, transparent);
      background-image: -moz-linear-gradient(45deg, rgba(255, 255, 255, 0.6) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, 0.6) 50%, rgba(255, 255, 255, 0.6) 75%, transparent 75%, transparent);
      background-image: -o-linear-gradient(45deg, rgba(255, 255, 255, 0.6) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, 0.6) 50%, rgba(255, 255, 255, 0.6) 75%, transparent 75%, transparent);
      background-image: linear-gradient(45deg, rgba(255, 255, 255, 0.6) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, 0.6) 50%, rgba(255, 255, 255, 0.6) 75%, transparent 75%, transparent);
      -webkit-background-size: 40px 40px;
         -moz-background-size: 40px 40px;
           -o-background-size: 40px 40px;
              background-size: 40px 40px;
    }
  "))),
  plotOutput('plot', width = "300px", height = "300px"),
  actionButton('goPlot', 'Go plot')
))

shinyApp(ui = ui, server = server)

Tentei seguir as sugestões acima ... mas não funcionou ...

Por favor, veja abaixo a minha tentativa, qualquer ajuda seria muito apreciada.

http://stackoverflow.com/questions/38339593/shiny-loading-bar-for-htmlwidgets

Também seria possível usar algo assim? ...

https://gist.github.com/eesur/cf81a5ea738f85732707

Acho que você poderia usar https://getbootstrap.com/docs/3.4/components/#progress -animated.

@ jcheng5 sugeriu ativar o "modo indeterminado" configurando value = NA . Mas dado que isso é chamado de "animado", talvez seja mais flexível adicionar um parâmetro animated , e então você poderia fazer withProgress(..., value = 1, animate = TRUE)