Change color of slider using updateSliderTextInput

Question

I am trying to change the color of the slide when updating its values. I have tried different ways without success. The following code does not run, but replicates what I am trying to do:

if (interactive()) {
  library("shiny")
  library("shinyWidgets")
  
  ui <- fluidPage(
    br(),
    sliderTextInput(
      inputId = "mySlider",
      label = "Pick a month :",
      choices = month.abb,
      selected = "Jan"
    ),
    verbatimTextOutput(outputId = "res"),
    radioButtons(
      inputId = "up",
      label = "Update choices:",
      choices = c("Abbreviations", "Full names")
    )
  )
  
  server <- function(input, output, session) {
    output$res <- renderPrint(str(input$mySlider))
    
    observeEvent(input$up, {
      choices <- switch(
        input$up,
        "Abbreviations" = month.abb,
        "Full names" = month.name
      )
      updateSliderTextInput(
        session = session,
        inputId = "mySlider",
        choices = choices,
        color = "red" # This is the line I need to add
      )
    }, ignoreInit = TRUE)
  }
  
  shinyApp(ui = ui, server = server)
}

Maybe has someone the answer to this?

Answer 1

I was able to give this some more thought and figured out a way to update the slider color based on an input. shinyWidgets::setSliderColor essentially just injects CSS to overwrite all the classes associated with the sliderInputs. So it needs to be included in the UI instead of the server. (Took a min to realize that).

I set up a blank uiOutput which is then updated by observing input$up with the new or default color.

Demo

ui <- fluidPage(
  br(),
  mainPanel(class = "temp",
    uiOutput('s_color'), # uiOuput
    sliderTextInput(
      inputId = "mySlider",
      label = "Pick a month :",
      choices = month.abb,
      selected = "Jan"
    ),
    verbatimTextOutput(outputId = "res"),
    radioButtons(
      inputId = "up",
      label = "Update choices:",
      choices = c("Abbreviations", "Full names")
    )
  )
)

server <- function(input, output, session) {
  output$res <- renderPrint(str(input$mySlider))
  
  # output$s_color = renderUI({})
  observeEvent(input$up, {
    choices <- switch(
      input$up,
      "Abbreviations" = month.abb,
      "Full names" = month.name
    )
    updateSliderTextInput(
      session = session,
      inputId = "mySlider",
      choices = choices
    )
    output$s_color = renderUI({ # add color 
      if (input$up == "Full names") {
        setSliderColor(c("Red"), c(1))
      } else {
        setSliderColor(c("#428bca"), c(1))
      }
    })
  }, ignoreInit = TRUE)
}

shinyApp(ui = ui, server = server)