Why is collaps not working in bootstrap?

Question

Ruby on Rails

There is this simple code:

%nav{role:'navigation', class:'navbar navbar-inverse'}
      %div{class: 'container'}
        %div{class: 'navbar-header'}
          = button_tag(type: 'button', class: 'navbar-toggle collapsed',
            data: { target: '#navbarCollapse', toggle: 'collapse' }) do
            %span{class: 'sr-only'}Toggle navigation
            %span{class: 'icon-bar'}
            %span{class: 'icon-bar'}
            %span{class: 'icon-bar'}
          = link_to 'Some title', '#', class: 'navbar-brand'
        %div{id: 'navbarCollapse', class: 'navbar-collapse collapse'}
          %ul{class: 'nav navbar-nav'}
            %li= link_to 'Help', '#'
            %li= link_to 'About Us', '#'
            %li= link_to 'Some text 1', '#'
            %li= link_to 'Some text 2', '#'

At resolution < 768, the menu icon appears as it should (it works), but when you click on it, the menu does not expand. Correct what I'm doing wrong?

Answer 1

The problem was due to the fact that in the file " application.js " I forgot to write:
//= require bootstrap-sprockets