我试图让bootstrap dropdown工作，bootstrap显示正确，但dropdown动作不工作，我怀疑这与jquery有关，但jquery工作得很好。
./Gemfile

gem "bootstrap", "~> 4.4"    
gem "jquery-rails", "~> 4.3"

字符串
./app/assets/stylesheets/application.scss

@import "bootstrap";

型
./app/javascript/packs/application.js

//= require bootstrap-sprockets
//= require jquery
//= require jquery_ujs
//= require bootstrap
//= require turbolinks
//= require_tree .

型
在我的浏览器控制台上调用

$('.dropdown-toggle')

型
工作正常，但当调用

$('.dropdown-toggle').dropdown()

型
说Uncaught TypeError: $(...).dropdown is not a function at <anonymous>:1:23
下面是从Bootstrap's navbar example复制的html

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNavDropdown">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
    </ul>
  </div>
</nav>

型
编辑：
Popper.js被正确地包含在内，我已经通过删除手动导入测试了这一点，我认为问题是当包含jquery和bootstrap时，因为一旦我删除了其中一个手动导入，下拉列表就会中断（不改变视图）