R Shiny grep javascript

Question

I want to be able to use grepl in a conditionalPanel function.

Here is a MWE. In this one, I test that my input is explicitely one of the possibilities.

library(shiny)

ui <- fluidPage(

  column(5, wellPanel(
    uiOutput("test")
  )
  ),

  column(7,
         conditionalPanel("input.essai_res == 'first choice.xlsx'",
                           p("test")
         )

  )
)

server <- function(input, output) {

  output$test <- renderUI({
    selectInput("essai_res", h3("Test"), c("first choice.xlsx", "second choice.xlsx"))
  })
}

shinyApp(ui = ui, server = server)

Instead of that, I'd like to be able to test that the string "first" is part of the choice for example.

I tried

conditionalPanel("grepl('first', input.essai_res)", p("test"))

conditionalPanel("'first'.test(input.essai_res)", p("test"))

the second one I did it to try a JavaScript command.

In those 2 cases, whatever the choice in the list, "test" always appears.

What can I do in order to have "test" appears only when "first" is part of the choices?

I add this comment to answer a question below about the context. The choices come from those command lines:

files_list <- list.files(path = "Data/", pattern = "\\.xlsx$|\\.xlsm$", full.names = TRUE)
files_names <- substring(files_list, 6)
files_list <- as.list(files_list)
names(files_list) <- files_names

if (length(files_list) == 0){files_list <- "No files in the folder \"Data\""}

output$path_res <- renderUI({
    selectInput("essai_a", h3("Title"), files_list)
  })

Answer 1

You can use includes but note that it will not work in IE:

library(shiny)

ui <- fluidPage(

  column(
    width = 5, wellPanel(
      selectInput("essai_res", h3("Test"), c("first choice.xlsx", "second choice.xlsx"))
    )
  ),

  column(
    width = 7,
    conditionalPanel(
      "input.essai_res.includes('first')",
      p("test")
    )
  )
)

server <- function(input, output) {
}

shinyApp(ui = ui, server = server)

Answer 2

With a regex: "(/first/).test(input.essai_res) ".