EDIT: I read the jQuery example a bit more, and added a code snippet doing what I think you were looking for.
I don’t know jQuery, so I couldn’t make much out of the example link. I took a guess on what you wanted, but I think the key idea is the use of renderUI and uiOutput even if my suggestion here misses the point.
To toggle a ui element:
If you specifically don’t want to use shinyjs, you could do something like this:
library(shiny)
ui <- shinyUI(fluidPage(
actionButton("btn", "Toggle Textbox"),
textOutput("btn_val"),
uiOutput("textbox_ui")
))
server <- shinyServer(function(input, output, session) {
output$btn_val <- renderPrint(print(input$btn))
textboxToggle <- reactive({
if (input$btn %% 2 == 1) {
textInput("textin", "Write something:", value = "Hello World!")
}
})
output$textbox_ui <- renderUI({ textboxToggle() })
})
shinyApp(ui, server)
To add and remove elements:
After reading a bit of the jQuery example, I think this is similar to what you were looking for:
library(shiny)
ui <- shinyUI(fluidPage(
sidebarPanel(
actionButton("add_btn", "Add Textbox"),
actionButton("rm_btn", "Remove Textbox"),
textOutput("counter")
),
mainPanel(uiOutput("textbox_ui"))
))
server <- shinyServer(function(input, output, session) {
# Track the number of input boxes to render
counter <- reactiveValues(n = 0)
observeEvent(input$add_btn, {counter$n <- counter$n + 1})
observeEvent(input$rm_btn, {
if (counter$n > 0) counter$n <- counter$n - 1
})
output$counter <- renderPrint(print(counter$n))
textboxes <- reactive({
n <- counter$n
if (n > 0) {
lapply(seq_len(n), function(i) {
textInput(inputId = paste0("textin", i),
label = paste0("Textbox", i), value = "Hello World!")
})
}
})
output$textbox_ui <- renderUI({ textboxes() })
})
shinyApp(ui, server)
The problem with this approach is that each time you press the add or remove button, all of the input boxes get re-rendered. This means that any input you might have had on them disappears.
I think you could get around that by also saving the current input values of the input boxes into a reactiveValues object, and setting the values from the object as the starting values of the re-rendered input boxes by using the value option in textInput. I’ll leave the implementation of that for now, though.