Rails chosen select example

chosen_select.js

$(function() {
  $('.chosen-select').chosen({
    allow_single_deselect: true,
    no_results_text: 'No results matched'
  });
});

example_form.html.slim

= simple_form_for @nato, url: { action: action } do |f|
  = f.input :member_countries, as: :country, input_html: { class: 'chosen-select', multiple: true }

Select for choosing multiple countries.