select2 in rails 5 => Javascript not executing

gistfile1.txt

js:
$(document).on('turbolinks:load',function(){
  $(document).ready(function(){
    $("#modalBtn").click(function(){
      $("#newProject").modal("show");
    });
    $("#newProject").on('show.bs.modal', function () {
      flatpickr('#project_deadline_for_budget_preparation', {
        altInput: true,
        altFormat: "F j, Y",
        dateFormat: "Y-m-d",
      });
      flatpickr('#project_expect_construction_start_at', {
        altInput: true,
        altFormat: "F j, Y",
        dateFormat: "Y-m-d",
      });
    });
  });
});

html:

%button.btn.btn-success.btn-sm{"data-target" => "#newProject", "data-toggle" => "modal", :type => "button", :id => "modalBtn"}
  New project
/ Modal
#newProject.modal.fade{"aria-hidden" => "true", "aria-labelledby" => "newProjectTitle", :role => "dialog", :tabindex => "-1"}
  .modal-dialog.modal-dialog-centered{:role => "document"}
    .modal-content
      .modal-header
        %h5#exampleModalLongTitle.modal-title New project
        %button.close{"aria-label" => "Close", "data-dismiss" => "modal", :type => "button"}
          %span{"aria-hidden" => "true"} ×
      = simple_form_for Project.new do |f|
        .modal-body