Javascript Bootstrap 4.1 js不工作

我正在尝试引导，但js在导航下拉+移动图标中不起作用

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

这是我的html：

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

---

关于js的其他主题与bootstrap的问题对我没有帮助…

我从来没有见过这样的东西，我想知道你是如何以这种方式使用bootstrap的。您的做法是完全错误的，您没有直接在html标记中导入.css/.js文件，而是在代码中的适当位置指定了这些库。您需要从头开始，了解如何使用引导，这里是一个很好的示例源代码：

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

---

不知道您在html中导入了哪些文件，但如果您没有导入bundle js文件，那么您也需要导入popper.js文件。要使引导程序正常工作，您总共需要以下4个文件：

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

bootstrap.min.css 建议使用jquery最新版本 popper.js bootstrap.min.js 第2、3、4号-订单事宜

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

希望这有助于

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

确保您必须在头部添加所有这些cdn

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

MaxCDN为引导的CSS和JavaScript提供CDN支持。您还必须包括jQuery：

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

MaxCDN：

  <div class="collapse navbar-collapse" id="navbarColor02">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">TEST <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" id="download">Pulse <span class="caret"></span></a>
          <div class="dropdown-menu" aria-labelledby="download">
            <a class="dropdown-item" href="https://jsfiddle.net/bootswatch/0mb9487u/">Open in JSFiddle</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/bootstrap.min.css">bootstrap.min.css</a>
            <a class="dropdown-item" href="../4/pulse/bootstrap.css">bootstrap.css</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="../4/pulse/_variables.scss">_variables.scss</a>
            <a class="dropdown-item" href="../4/pulse/_bootswatch.scss">_bootswatch.scss</a>
          </div>
        </li>
    </ul>
  </div>
</nav>

---

CSS和JS应该在head中声明。我解决了它。这是所需js文件中的订单问题。我不得不用jquery>popper>bootstrap更改顺序