Access by jQuery UI elements created in server part of Shiny App

Question

I want to pass to Shiny ID of an element of specific pseudo-class when it is clicked. Everything is working fine if UI elements are created in UI part of Shiny app. But when UI is created on server side (by renderUI ) it doesn't work. Below is reproducible example.

library(shiny)
library(shinyjs)

ui <- fluidPage(
  useShinyjs(),
  fluidRow(
    tags$div(id = "ui1", class = 'shiny-html-output shiny-bound-output',
      tags$a(id = "ID1", class = "my-class", href = "#", 'Link 1')
    ),
    uiOutput("ui2")
  )
)

server <- function(input, output) {
  output$ui2 <- renderUI({
    tags$a(id = "ID2", class = "my-class", href = "#", 'Link 2')
  })

  shinyjs::runjs(
  '$(document).ready(function(){
    $(".my-class").click(function(){
      alert($(this).attr("id"));
    });
  });')
}

shinyApp(ui, server)

Answer 1

$(document).ready approach won't work because server will not render it outputs until the DOM is ready. Use session$onFlushed instead, with once parameter set to TRUE , then shiny will run the function only once, not on every session flush.

This will work:

library(shiny)
library(shinyjs)

script <- "$('.my-class').click(function(){
alert($(this).attr('id'));
});"

ui <- fluidPage(
  useShinyjs(),
  fluidRow(
    tags$div(id = "ui1", class = 'shiny-html-output shiny-bound-output',
             tags$a(id = "ID1", class = "my-class", href = "#", 'Link 1')
    ),
    uiOutput("ui2")
  )
)

server <- function(input, output, session) {

  output$ui2 <- renderUI({
    tags$a(id = "ID2", class = "my-class", href = "#", 'Link 2')
  })


  session$onFlushed(function() {
    shinyjs::runjs(script)
  }, once=TRUE)

}

shinyApp(ui, server)