***問題**  
Bootstrapのnavでheaderにドロップダウンメニューを導入しているのですが、ドロップダウンが開く場合と開かない場合があり困っています。

navbarには現在ビューのあるリンクとしてHome画面とEdit画面（ドロップダウン内）へのリンクがあるのですが、それらのリンク先へ遷移した直後にドロップダウンメニューが動かなくなってしまいます。しかし、ブラウザで再読込（更新）するとドロップダウンメニューが動くようになります。

***やったこと**  
jsの問題かと思い調べてみたのですが、なかなか適切な資料も見つからず解決には至っていません。

下記にコードを添付いたします。よろしくお願いいたします。

routes.rb

```

    Rails.application.routes.draw do
     root   'static_pages#home'
     get    '/help' => 'static_pages#help'
     get    '/about' => 'static_pages#about'
     get    '/contact' => 'static_pages#contact'
     get    '/signup' => 'users#new'
     get    '/login' => 'sessions#new'
     post   '/login' => 'sessions#create'
     delete '/logout' => 'sessions#destroy'
     resources :users
     resources :account_activations, only: [:edit]
     resources :password_resets,     only: [:new, :create, :edit, :update]
    end
    
```

_header.html.erb

```

    <nav class="navbar navbar-fixed-top navbar-expand-lg navbar-dark bg-primary">
     <div class="container">
      <a href="/" class="navbar-brand">
       Body-Weight App
      </a>
      <ul class="navbar-nav">
       <% if logged_in? %>
        <li><a  href="/" class="nav-link">Home</a></li>
        <li><a  href="#" class="nav-link">Help</a></li>
        <li  class="dropdown">
          <a href="#" class="nav-link dropdown-toggle" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
            Account<span  class="caret"></span>
          </a>
           <div class="dropdown-menu" aria-labelledby="navbarDropdown">
             <a  href="/users/<%= current_user.id.to_s %>/edit" class="dropdown-item">Settings</a>
             <div class="dropdown-divider"></div>
             <a  class="dropdown-item" rel="nofollow" data-method="delete" href="/logout" >Log Out</a>
           </div>
        </li>
      <% else %>
        <li><a  href="#" class="nav-link">Help</a></li>
      <% end %>
    </ul>
    
```

  

_head.html.erb

```

    <head>
     <title><%= full_title(yield(:title)) %></title>
     <%= csrf_meta_tags %>
    
     <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
     <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css" integrity="sha384-9gVQ4dYFwwWSjIDZnLEWnxCjeSWFphJiwGPXr1jddIhOegiu1FwO5qRGvFXOdJZ4" crossorigin="anonymous">
    
     <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
     <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>
    </head>
    
```

application.html.erb

```

    <!DOCTYPE html>
     <html>
      <%= render "layouts/head"%>
      <body>
       <%= render "layouts/header" %>
       <div class="container">
        <%= render "layouts/flash" %>
        <%= yield %>
        <%= render 'layouts/footer' %>
      </div>
      <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
      <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
      </body>
    </html>
    
```

application.js

```

    // This is a manifest file that'll be compiled into application.js, which will include all the files
    // listed below.
    //
    // Any JavaScript/Coffee file within this directory, lib/assets/javascripts, or any plugin's
    // vendor/assets/javascripts directory can be referenced here using a relative path.
    //
    // It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
    // compiled file. JavaScript code in this file should be added after the last require_* statement.
    //
    // Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
    // about supported directives.
    //= require rails-ujs
    //= require turbolinks
    //= require_tree .
    //= require jquery3
    //= require popper
    //= require bootstrap-sprockets
    
```

application.scss

```

    /*
     * This is a manifest file that'll be compiled into application.css, which will include all the files
     * listed below.
     *
     * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
     * vendor/assets/stylesheets directory can be referenced here using a relative path.
     *
     * You're free to add application-wide styles to this file and they'll appear at the bottom of the
     * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
     * files in this directory. Styles in this file should be added after the last require_* statement.
     * It is generally better to create a new file per style scope.
    
     */
     @import 'bootstrap';
    
    
    
     $main-blue:#428bca;
     $light-gray:#777777;
    
     li{
       list-style: none;
     }
    
    
     .dropdown-item{
       color:$main-blue;
     }
    
    
     .footer{
       margin-top: 100px;
       border-top: 1px solid $main-blue;
       small{
         float:left;
         color:$main-blue;
       }
       ul{
         float:right;
       }
       li{
         float:left;
         margin-left: 15px;
       }
       a{
         color:$main-blue;
       }
     }
    
```
CC BY-SA 4.0
2019-06-26T08:50:19.457
56111
2019-06-26T21:17:50.937
2019-06-26T21:17:50.937
32986
34872
question
javascript ruby-on-rails bootstrap bootstrap4
Bootstrapのドロップダウンが開かないことがある
自己解決  
gemですでに導入してるのにもかかわらずcdnでも導入してしまったのが原因でした。
CC BY-SA 4.0
2019-06-26T09:30:20.897
56113
2019-06-26T09:30:20.897
34872
56111
answer