checkboxGroupInput - set minimum and maximum number of selections - ticks

Question

Here is example code with check-box group input:

library(shiny)

server <- function(input, output) {
  output$Selected <- renderText({
    paste(input$Sele         


        

Answer 1

You can use a little JavaScript to do it:

## In a file named 'js4checkbox.js' in your app folder :
$(document).ready(function(){
  $('input[name=SelecetedVars]').on('click', function(event){
    if($('input[name=SelecetedVars]:checked').length > 3){
      $(this).prop('checked', false);
    }
  });
  $('input[name=SelecetedVars]').on('click', function(event){
    if($('input[name=SelecetedVars]:checked').length == 0){
      $(this).prop('checked', true);
    }
  });
});

And in your ui add:

fluidPage(
  includeScript(path = "js4checkbox.js"),
  ...
)

I don't know why but it doesn't work well in the RStudio Viewer so open it in your browser.

For the JavaScript code see this post