[javascript] Bootstrap 4 Dropdown Menu not working?

I copied the official Bootstrap 4 example for dropdown menus but it is not working, that is nothing is dropped down.

<li class="nav-item dropdown">
    <a class="nav-link dropdown-toggle" href="#" id="dropdown01" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown</a>
    <div class="dropdown-menu" aria-labelledby="dropdown01">
    <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>

A simple answer is to replace this line:

<script type="text/javascript" src="your_directory/bootstrap.min.js"></script>

for this other:

<script type="text/javascript" src="your_directory/bootstrap.bundle.min.js"></script>

include them with this order this will work i dont know why :D

<!-- jQuery -->
<script src="js/jquery-3.4.1.min.js"></script>

<!-- Popper -->
<script src="js/popper.min.js"></script>

<!-- Bootstrap js -->
<script src="js/bootstrap.min.js"></script>

This is my solution

I just downloaded jquery's latest version from their official website and then added it as a js file in my project folder and then to my HTML file. After that it was working fine for me

I used NuGet to install BootStrap 4. I was also having issues with it not displaying the Dropdown on click. It kept throwing an error in jquery base on what the Chrome console was telling me.

I originally had the following

<%-- CSS --%>
<link type="text/css" rel="stylesheet" href="/Content/bootstrap.css" />

 <%-- JS --%>
<script type="text/javascript" src="/Scripts/jquery-3.3.1.min.js"></script>
<script type="text/javascript" src="/Scripts/bootstrap.min.js"></script>

But I changed it to use the bundled version instead and it started to work

<%-- CSS --%>
<link type="text/css" rel="stylesheet" href="/Content/bootstrap.css" />

<%-- JS --%>
<script type="text/javascript" src="/Scripts/jquery-3.3.1.min.js"></script>
<script type="text/javascript" src="/Scripts/bootstrap.bundle.min.js"></script>

Assuming Bootstrap and Popper libraries were installed using Nuget package manager, for a web application using Visual Studio, in the Master page file (Site.Master), right below where body tag begins, include the reference to popper.min.js by typing:

<script src="Scripts/umd/popper.min.js"></script>

Here is an image to better display the location:

Notice the reference of the popper library to be added should be the one inside umd folder and not the one outside on Scripts folder.

This should fix the problem.

It's an issue with popper.js file. What I found at the official site was that bundle files include popper in itself but not jquery. I managed to fix it by adding link to these files:

bootstrap.bundle.js
bootstrap.bundle.min.js

I removed popper.js however since it comes within the bundle file.

It needs to be /bootstrap.js, not /bootstrap.min.js.

try to add these lines at the end of the file

<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
</body>
</html>

You need to enqueue the script bootstrap.js or bootstrap.min.js. I had the same problem with bootstrap 4.5.3 and the menu worked when I enqueued one of the above scripts. It can be either.

Via JavaScript Call the dropdowns via JavaScript:

Paste this is code after bootstrap.min.js

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

Also, make sure you include popper.min.js before bootstrap.min.js

Dropdowns are positioned thanks to Popper.js (except when they are contained in a navbar).

Make sure to include the Bootstrap CSS either via the Bootstrap CDN or download it and link it locally

Add this code to your jquery

  $('.dropdown').click(function(){

       $('.dropdown-menu').toggleClass('show');

   });