What is the best way to retrieve the focused element in a shiny application?

Question

What is the best way to retrieve the focused element in a shiny application?

I'm trying to figure out if there's a way to determine in shiny whether the user is focused on a text-field or select field. My website contains various elements such as plots, tables, numerical inputs, and buttons.

Currently, I have implemented the following script:

library(shiny)
ui <- fluidPage(
  tags$script('$(document).ready(function(){ $("*").focus( function(e){ Shiny.setInputValue("focusedElement", e.target.id);}); }); '),
  textOutput("output1"),
  textInput(inputId = "text1", label = 'Text1', value = ""),
  numericInput(inputId = 'num1',label = 'Num1', value=5),
  selectInput(inputId = 'select1', label='Select1',choices = c(1,2,3)),
  plotOutput('plot'),
  actionButton('btn','Btn'),
  DT::dataTableOutput('table'),
  
)

server <- function(input, output, session) {
  output$output1 <- renderText({ 
    print(input$focusedElement)
    input$focusedElement })
  output$table<- DT::renderDataTable(iris)
  output$plot<-renderPlot(plot(iris[,c(3,4)]))
}

shinyApp(ui, server)

Despite focusing on every single input and background, only the Text-Input, Numerical-Input, and Buttons seem to work. But why is this happening? (Check the console output, select1 was certainly focused at some point but never printed, along with the search bar, plot, and background.)

https://i.sstatic.net/g7FQb.png

Please feel free to suggest entirely different approaches or correct my code style.

In essence, all I want to know is whether the user is currently in a text field (such as text1 or num1, or the table's search bar) or interacting with a button.

javascript r shiny focus

Answer 1

Answer №1

It seems that the issue is arising because the element in focus is an option element, rather than the main select element itself.

To address this, you can utilize the selectizeInput function to activate an action upon focus, utilizing the onFocus option.

library(shiny)

js <- "function() {
  Shiny.setInputValue('focus', true, {priority: 'event'});
}"

ui <- fluidPage(
  selectizeInput(
    "ID", "LABEL", 
    choices = list("A", "B", "C"),
    options = list(
      onFocus = I(js)
    )
  )
)

server <- function(input, output, session) {
  observeEvent(input[["focus"]], {
    showNotification("FOCUS!!!")
  })
}

shinyApp(ui, server)

EDIT

An additional option to consider is the onBlur option, which executes a function when the focus is lost. This allows for actions like:

onFocus <- "function() {
  Shiny.setInputValue('focus', 'SELECT');
}"
onBlur <- "function() {
  Shiny.setInputValue('focus', null);
}"

ui <- fluidPage(
  selectizeInput(
    "ID", "LABEL", 
    choices = list("A", "B", "C"),
    options = list(
      onFocus = I(onFocus), onBlur = I(onBlur)
    )
  )
)

Apply a similar approach to other widgets of interest, ensuring that the Shiny variable input$focus accurately reflects the currently focused element within the widgets being examined, and defaults to NULL if none are focused.

Answer 2

It seems that the issue is arising because the element in focus is an option element, rather than the main select element itself.

To address this, you can utilize the selectizeInput function to activate an action upon focus, utilizing the onFocus option.

library(shiny)

js <- "function() {
  Shiny.setInputValue('focus', true, {priority: 'event'});
}"

ui <- fluidPage(
  selectizeInput(
    "ID", "LABEL", 
    choices = list("A", "B", "C"),
    options = list(
      onFocus = I(js)
    )
  )
)

server <- function(input, output, session) {
  observeEvent(input[["focus"]], {
    showNotification("FOCUS!!!")
  })
}

shinyApp(ui, server)

EDIT

An additional option to consider is the onBlur option, which executes a function when the focus is lost. This allows for actions like:

onFocus <- "function() {
  Shiny.setInputValue('focus', 'SELECT');
}"
onBlur <- "function() {
  Shiny.setInputValue('focus', null);
}"

ui <- fluidPage(
  selectizeInput(
    "ID", "LABEL", 
    choices = list("A", "B", "C"),
    options = list(
      onFocus = I(onFocus), onBlur = I(onBlur)
    )
  )
)

Apply a similar approach to other widgets of interest, ensuring that the Shiny variable input$focus accurately reflects the currently focused element within the widgets being examined, and defaults to NULL if none are focused.

What is the best way to retrieve the focused element in a shiny application?

Answer №1

EDIT

Similar questions

Attempting to upload an item using ThreeJs

Is there a way to send a variable to the alert function using $.ajax()?

I encounter issues when trying to run "yarn start" following the integration of tailwindcss into my React project

Instructions on how to submit a form using a button while also clicking on an anchor link simultaneously

How to replace text using jQuery without removing HTML tags

I am wondering why the vue-router is only changing the URL and not displaying the corresponding view component

Is it necessary to wait for client responses in order to execute code with socket.io?

Leverage the selected values to dynamically generate a table using jQuery

How can I utilize JavaScript to retrieve the background color of a table cell upon clicking?

How can I calculate the total sum of values in an array retrieved from an API call?

Communication between React components

Error occurs when attempting to access window.google in Next.js due to a TypeError

Is there a way to prevent jQuery.ajax() from displaying errors in the console?

Focusing on a text field after reloading a different div with AJAX

The input type "number" does not seem to be compatible with the currency pipe feature

Using jQuery to populate an array and add commas to a mailto link

Verify the input fields for errors upon tab press or when moving to a different field and display any errors that may occur

Is there a way to remove the old React component when there are two instances of it still active while passing variables?

Individualize JavaScript clients for each module in ExpressJS

Leveraging JSON data in subsequent GET request in Ionic 3