Navbar menu input

To capture the currently selected tab to subsequently perform actions on the server side, updating the selected tab based on a button click.

1. Add an id attribute to tabler_navbar_menu().

tabler_navbar_menu <- function(..., id = NULL) {
  tags$ul(
    id = id, 
    class = "nav nav-pills navbar-nav",
    ...
  )
}

2. Create the JS navbarMenuBinding looking for the navbar-nav class in the find method.

find: function(scope) {
  return $(scope).find('.navbar-nav');
}