Good night and thanks for reading me

I am working on a shiny manager protected application and would like to add an initial animation to the home panel, but what I have tried so far does not work. Does anyone know if it is possible to add such animation? Or some way to correct the code to make it work? I appreciate your help

The code im using is the following:

js <- "
$(document).ready(function(){
  $('#plotContainer').on('show', function(event){
    $(this).css('opacity', 0).animate({opacity: 1}, {duration: 1000});
  });
});
"


credentials <- data.frame(
    user = c("shiny", "shinymanager"),
    password = c("azerty", "12345"),
    stringsAsFactors = FALSE
)

library(shiny)
library(shinymanager)

ui <- fluidPage(
    tags$h2("My secure application"),
    verbatimTextOutput("auth_output")
)


ui <- secure_app(
    tags$head(tags$script(HTML(js))),
    ui, choose_language = TRUE)


server <- function(input, output, session) {
 
    res_auth <- secure_server(
        check_credentials = check_credentials(credentials)
    )
    
    output$auth_output <- renderPrint({
        reactiveValuesToList(res_auth)
    })
    
    observe({
        print(input$shinymanager_where)
        print(input$shinymanager_language)
    })
    
    
    
}

shinyApp(ui, server)